


learning to take

by parsnipit



Category: Undertale (Video Game)
Genre: Alternate Universe - Vampire, Angst, Angst with a Happy Ending, Blood Drinking, Cooking, Cuddling & Snuggling, Domestic Fluff, Dorks in Love, Emotional Hurt/Comfort, Emphasis on Comfort, Established Relationship, Fluff, Healthy Relationships, M/M, Praise Kink, Protective Grillby, Protectiveness, Soulmates, Vampire Gaster, like seriously guys there's So Much snuggling, oh surprise it's a
Language: English
Status: Completed
Published: 2019-12-27
Updated: 2020-02-02
Packaged: 2021-02-26 07:20:43
Rating: Teen And Up Audiences
Warnings: No Archive Warnings Apply
Chapters: 5
Words: 24,342
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/21979483
Author URL: https://archiveofourown.org/users/parsnipit/pseuds/parsnipit
Summary: Dr. Gaster is the happiest monster on earth. He’s got a fantastic job, a cozy house, food and friends aplenty, and the world’s most loving soulmate—then he's turned into a vampire, which, you know, kind of throws a wrench into his idyllic lifestyle. But he's going to make it work! Even if it means he has to suffer, he's not going to let his newfound needs hurt anyone around him. He's going to deal with this alone, because that's clearly what any mature and independent monster would do.Leastways, that's the plan until Grillby finds out.
Relationships: W. D. Gaster/Grillby
Comments: 61
Kudos: 146





	1. cherry cordials

**Author's Note:**

  * Inspired by [Blaze of Night](https://archiveofourown.org/works/16153151) by [Anchestor](https://archiveofourown.org/users/Anchestor/pseuds/Anchestor). 

**Notes for the Chapter:**

> warnings: violence, blood, minor injuries, death
> 
> guys i am!!! so excited to finally post this!!! it's going to be a fairly short fic, but i've been having a blast writing it so far! it was heavily inspired by anchestor's [blaze of night](https://archiveofourown.org/works/16153151/chapters/37742594), which you should absolutely read if you love vampires and/or grillster, because it is p h e n o m e n a l and inspired in me a Great Need for more vampire!grillster fics, and thus this bad boy was born! i hope you all enjoy!!! feel free to yell at me about vampires or grillster or anything u want over at my tumblr, [parsnipit!](https://parsnipit.tumblr.com/)

On nights like this, sitting on a counter in a warm kitchen with the love of his life close at hand and the Gyftmas lights twinkling outside, Gaster realizes that he’s the happiest monster alive. The aforementioned love of his life currently hums along to quiet jazz music, sprinkling powdered sugar into the pink fondant he’s mixing. Gaster watches him with nothing short of utter adoration—which is perhaps a mistake, he realizes, as he dumps maybe a _little_ too much brandy into a bowl of cherries. He quickly straightens the bottle of brandy, setting it aside and peeking over to make sure Grillby hasn’t noticed. When Grillby continues to stir, folding the fondant up and over itself, Gaster drains off some of the brandy in the bowl and then sets the cherries aside to soak.

“Cherries for tomorrow morning are prepped and soaking,” he informs Grillby, swinging his legs over the side of the counter. “Do you need help with anything else for tonight’s batch?”

“Could you temper the chocolate for me?”

Gaster winces. Chocolate tempering—a finicky thing that has just as much to do with science as it does cooking. He is good at exactly one of those things, and when it comes to tempering, that’s hardly enough (as he has discovered through a series of unfortunate attempts). Still, he’s seen Grillby do it enough that he thinks he can get the process started. “Well, I can try. You may have to rescue it.”

Grillby chuckles, gravelly and warm. “That’s alright.”

Gaster slips off of the counter and retrieves the dark chocolate, carefully chopping it into small pieces before scooping it into the double boiler. He slides a candy thermometer in, then gets to stirring gently as the chocolate melts. “What was the temperature for the dark?”

“A little under a hundred and twenty Fahrenheit,” Grillby says, rolling the fondant out onto a sugar-dusted surface before continuing to knead it. “Then take it off and let it cool to eighty-two, add the rest of the chocolate and let it melt some, reheat to eighty-nine. Try to do it slowly; I need a little more time to finish the fondant.”

Gaster lets out a nervous breath. “Oookay.”

“Hey, c’mon, you can do this. If you don’t think it’s working, we’ll switch.”

“Harder to mess up fondant than to mess up chocolate, huh?”

“You know it.”

Gaster makes it to the first cooling, then readily switches places with Grillby. The fondant has been mostly finished, by the time he gets to it—he only has to wrap pieces of it carefully around each of the liquor-soaked cherries they’d prepared early that morning. When the cherries have been lovingly cocooned in a layer of pink sugar, he and Grillby dip them into the (beautifully tempered) dark chocolate. Once the first layer of chocolate has semi-hardened, they dip them again, for Extra Chocolate Security. Then the cherries are set out on a cookie sheet to finish cooling, and Gaster looks wistfully at them.

“Ah, and now we wait. Patience, my great nemesis,” he says.

Grillby wraps his arms around Gaster’s waist from behind, nuzzling into his shoulder. His sparks tickle where they brush Gaster’s jaw and neck. “Just a few days until they’re done. They’ll be worth it. But here, for your hard work—”

Gaster watches eagerly as Grillby rummages through the fridge, pulling out a single cherry cordial. “Oooh, when’d you make that?”

“I made a batch a few days ago, just to test the recipe,” Grillby admits, tossing the cordial to him. Gaster catches it, licking his teeth. “Go ahead. Payment for the piper, lest he come back to haunt me.”

“Mm, payment accepted.” Gaster pops the cordial into his mouth, cracking the chocolate between his teeth and sighing happily as he tastes the sweet syrup of dissolved fondant and the sour prickle of cherry. “Delicious, love.”

“Thank you.” Grillby drops a kiss onto his cheek, and Gaster lids his eyes and purrs. “Of course, I couldn’t have done it without my sous.”

“Oh, you flatter me.”

“I try.”

“If you aren’t careful, I’ll be spoiled.”

“I wouldn’t have you any other way.”

A grin dances across Gaster’s face, and he pulls the hood of Grillby’s sweatshirt up over his elemental’s head, then darts in to kiss him. He cradles Grillby’s face gently in his hands, breathes in the woodsmoke scent of him and understands what it is like to be absolutely, perfectly, ridiculously in love.

“You know,” Grillby says, just a touch breathlessly, when Gaster pulls back, “there’s a way to make cherry cordials using an enzyme called invertase.”

Gaster makes a point of shivering, leaning more heavily against Grillby. “Oooh, baby,” he says, trying his best not to giggle at his own attempt at sultry, “I love it when you talk science to me. Tell me more.”

“It’s, uh—you can buy it. You soak the cherries like normal, and then it dissolves the fondant when you let it sit, just like the brandy does, so you get the liquid center. Doesn’t taste quite as classic, but it’s non-alcoholic, so it’s better if you’re going to be feeding rugrats. I looked it up and it works by hydrolyzing sucrose into monosaccharides.”

“Mmm.” Gaster slides his hands beneath Grillby’s shirt, running them over the hard plane of Grillby’s back. “That’s my clever boy.”

Grillby gulps.

“Did you look it up just for me?” Gaster asks, peering innocently at him. 

“Of course.”

“Heh heh.” Gaster grins. His soul is so _warm._ “Thank you.”

Grillby brings his hands up, gently cupping Gaster’s face and brushing his thumbs over his cheeks. He fits their mouths together again, and Gaster inhales smoke and fire and couldn’t stop the purr that rattles his ribcage if he’d tried. “Bed?” Grillby offers hopefully when they part.

“Oh, as much as I’d love to, I can’t,” Gaster says, although he’s every bit reluctant to leave when he could have _this hot bod_ in a bed with him doing very, very unspeakable things. “I have a meeting tomorrow, and I haven’t finished proofing my reports yet.”

“Wings,” Grillby scolds gently. “You must have known that putting that off for so long would only stress you out. When are you going to sleep, if you’re up working all night?”

Gaster squirms. “Tomorrow night, probably?”

Grillby pulls back to frown at him, and Gaster whines petulantly. “Come on. You know better.”

“I know, I know. It’s just—it’s _Valentine’s Day,_ and I got so busy decorating and buying gifts and writing cards and everything, and work kind of fell to the wayside.”

“You didn’t have to help me today, if you had work to do. I would have understood.”

“But I wanted to!” Gaster protests. “I was so excited to spend time with you, Grillby. And today was really fantastic—it’s worth a single sleepless night, I promise. I’ll come nap with you after my meeting tomorrow, how about that?”

Grillby sighs fondly at him. “Alright, alright. Just don’t make it a habit, okay?” He presses a kiss to Gaster’s forehead. “We finally broke that one.”

“Yeah.” Gaster beams at him. “We did.”

Because they are capable of doing goddamn _anything_ together.

The two of them separate reluctantly, although Gaster can’t resist sneaking in a _few_ more nuzzles as he pulls his overcoat and scarf on. “Well, then, _I_ am off to do some great goddamn work,” Gaster says, pecking Grillby’s cheek. “I’ll see you tomorrow.”

“See you,” Grillby says, hugging him close before releasing him. “Hey, and guess what?”

“You love me!” Gaster guesses cheerfully, skipping down Grillby’s porch steps and into the street. The snow crunches and squeaks beneath his boots, and the false starlights above him gleam hard and bright and perfect. “Guess who loves you?”

Grillby smiles, and holy _fuck,_ what wouldn’t Gaster do for that smile? “You do.”

“Hell yeah I do.” Gaster winks. “Don’t forget it, sparks. Sleep tight.”

The walk back to his house is a short, chilly one, and he takes it slowly. Around him, Snowdin gleams with festive lights—reds and blues and greens, yellows and oranges and purples. The entire town has been festooned in tiny, glowing crystals that dapple the snow with halos of color. The holiday season will be ending soon, with Valentine’s Day, but Snowdin has always been fond of flaunting its holiday lights for as long as monsterly possible—and what better town to do so? Snowdin is _beautiful_ at night. There are days when Gaster misses the hustle and bustle of the capital, but days like this?

Days like this, he can’t imagine belonging anywhere else. He’s home.

When he reaches his house, he stops on the street for a moment, tipping his head back. Snowflakes sprinkle his cheeks in little cold kisses. The endless fog of the cavern ceiling roils high above him. If he tries hard enough, he can almost pretend they’re the clouds he was born under so very, very long ago. He shuts his eyes for a moment. Only a moment. Just long enough to breathe in the crisp, cold air and remember where he was born. Just one goddamn moment.

It’s a moment too long.

Something slams into him, and he topples back into the snowdrifts near his porch. A heavy weight lands on his chest, and then there are hands clawing at his scarf and fangs flashing far, far too close to his face. He is, firstly, stunned, because he’d been having a _really nice moment there._ He is, secondly, pissed. As soon as he’s caught his bearings, he lashes out. His knuckles crack against the monster’s cheek. Like. _Legitimately_ crack, because holy _fuck,_ it’s like punching stone.

Gaster jerks his arm back with a (kind of humiliating, to be honest) yelp of pain, and the monster cackles. “Oh my god, a _skeleton._ I thought you guys were supposed to be super powerful or som—”

Behind them, Gaster’s blaster screams with fury. The monster’s eyes (red, they’re so _red)_ go round seconds before a blaze of white light sears over the both of them. It barely clips the monster, because they curl their body down with whiplash speed. The movement brings their face eerily close to Gaster’s, and he can see something liquid and red smeared at the corner of their mouth. They smell like blood and sweat and things unfathomably dark. 

“Hot damn,” they say. “You _are_ dangerous. Noted.”

Then their hand is on Gaster’s jaw, forcing his head to the side. He jerks his legs up, driving his knee into the monster’s back as hard as he can, but every bit of them is as cold and unyielding as their face was. “Get off!” he shouts, another blast humming to life in his blaster’s jaws—but he dares not fire it when he can’t see his target clearly, not with his _house_ right behind them. “Fuck, let go of me, let _go—”_

“I will, I will,” the monster assures him. Hot breath ghosts across his neck, and he rattles in revulsion. His fingers twitch, and a bone attack begins to manifest behind the monster. With a furious growl, he pulls his attack forward. In the very same moment, something sharp and vicious and _awful_ sinks into the vertebrae of his neck. It leaves him breathless with surprise and agony, because _wow,_ that hurts a lot more than he ever thought something could hurt. 

Then the monster begins to pull, begins to tear something vital and valuable and _intimate_ from his very soul, and Gaster is blind with pain and _screaming._

When the bone attack hits, the monster flinches, but they don’t retreat. Instead, they huddle down against Gaster, and they bear it. That’s actually kind of insulting. Gaster may not be a soldier, but he’s no _pushover,_ and the monster isn’t even attempting a rational defense. Their focus, it seems, is entirely on causing Gaster an indescribable amount of agony—and _terror,_ because he knows, in the visceral way all animals know death, that he’ll be dust in minutes if this continues. He lashes out with his magic, and relief floods him when he hears the monster’s soul ping blue. Thank the stars. With one violent heave, he shoves the monster off of him and scrambles to his feet.

Immediately, a wave of dizziness overtakes him. He sways on his feet, his eyelights flickering erratically. The strange monster, on the other hand, is up and balanced within seconds. They scowl at him, licking foul, bright red from their fangs. “What the hell,” Gaster pants, “do you _want?”_

“Your magic, sweetheart,” the monster says, “so stop wasting it.”

They lunge for him, and he stumbles backwards, pushing with his blue magic—but it’s faltering, now, weakened by whatever the hell that monster did to his soul. The monster pushes him back against the front of his house, leering. 

“Now, where were we?”

Gaster opens his mouth to shout for help—someone must have heard his scream earlier, someone must be coming to save him, _someone—_ and the monster presses their hand to his mouth. “Do _not_ shout again,” they say. “Listen, this is going to hurt a lot less if you just—”

Gaster _bites._ His teeth aren’t fangs, but he’s damn well omnivorous, and his incisors and canines are quite fucking capable of tearing flesh. Cold skin breaks beneath his jaws, and blood bursts into his mouth. The monster cries out in pain, jerking back and holding their hand close to their chest. For a moment, the two of them regard each other warily.

“Fuck,” the monster says. “You really should not have done that.”

Gaster opens his mouth to respond, but before he can, something crackles to life behind him—something crackles, something snaps, something burns and blazes and _roars. “Get the fuck—”_ Shadows coil and lash against the snow, against the far walls, against the fog rolling high above them. Everything washes into blurs of yellow and white and gray. The snow begins to sizzle. _“—away from him!”_

Gaster stumbles backwards, into the inferno, and it curls possessively around him with a furious shriek. In the distance, he hears the shouts and howls of the Canine Unit as they draw closer. He does not see the monster die. He does not see anything but fire, but light and movement and all the patched darknesses in between. It takes several minutes for that fire to cease roaring, for the smoke to clear from his eyes, and when it does, he’s left with a petrified elemental and a sick, sinking feeling in his chest.

“Wings?” Grillby asks, his flames whirling around Gaster in endless anxiety. Powdery ashes settle on his shoulders like snow. “Wings, oh, Wings, my Wings, are you alright, are you hurt? I heard you scream—what’s wrong? What can I do?”

Gaster wraps his arms tightly around himself, sucking in a shaky breath—then another, and another, and oh dear he’s breathing a little too fast now isn’t he, he’s starting to feel rather light-headed and a tad bit nauseous if he’s telling the truth—

“Wings?” Grillby flickers, dims, growing smaller—struggling towards his ordinary form. As soon as he grasps it, his hands settle on Gaster’s shoulders, brush away the ashes. “Hey, hey, breathe, okay? You’re fine, you’re safe, I’ve got you. Breathe. In, out, in, out, c’mon, you’ve got it. Safe, sweetpea, you’re safe.”

Gaster struggles to breathe with Grillby, and it helps, some. The roof of his mouth stops buzzing, and the strange colors flickering in his vision begin to dull. He stumbles over his words as he struggles to tell Grillby what the _fuck_ had happened. “I don’t—I don’t know what happened, I was just walking home and they came out of nowhere and attacked me and I don’t know what I did, I don’t know what I did wrong I don’t know why they did that I don’t know—”

“Oh, no.” Grillby hugs him close, and Gaster stiffens in his grip—then one warm, soft hand cradles the back of his skull, and he all but collapses against his soulmate, his breath hitching as he remembers what it feels like to be held by someone who has always, always been safe. “No, you didn’t do anything wrong, not a single thing, I’m sure of it. We can tell the Guard what happened in a few minutes, but right now, I need to know if you’re hurt anywhere. Can I take a look at you?”

“Not hurt,” Gaster says, which is a lie, so he doesn’t quite know why he says it in the first place. Force of habit, perhaps (though a long-broken habit he’s disappointed to be lapsing back into).

“I know maybe you don’t feel hurt, but you’re probably about as high on adrenaline as a monster can get, right now. Let me look at you.” Grillby gently nudges him back, holding him at arms’ length. As soon as Grillby’s steady warmth is removed from his bones, he begins to rattle. Grillby’s eyes rake over him, and he murmurs quiet consolations as they do, murmurs _it’s okay,_ and _shh-shh-shh, I’m here_ and _breathe, Wings, just breathe with me._

As soon as Grillby has satisfied himself with the knowledge that Gaster isn’t about to immediately keel over and die, he hauls Gaster back into a hug. Gaster melts into him with a wretched whine and buries his face against Grillby’s neck. Soft fingers brush across the wound on his neck, and he winces. The fingers move away.

“This and your hand,” Grillby says, swaying gently in place. It reminds Gaster of all the times he’s startled awake to find Grillby breathing hard beside him, sparking and terrified after another nauseating nightmare—those times when Gaster wraps Grillby in his arms and lulls him back to sleep with slow rocking and tender words. The thought of that makes him want to cry. “Those are the only injuries I see. You’re gonna be fine, baby boy, just fine.”

“Grillby? Dr. Gaster?” One of the guards comes to a stop a few feet away from them, eyes averted. “Dr. Nestor is on her way. She’ll tend to any injuries and take medical notes for the court, and we’ll take your statement after that. She should be here in a just a few minutes; is there anything you need immediately?”

Grillby looks expectantly at him. “Anything you need, Wings?”

Gaster shakes his head.

“No,” Grillby says. “We’re alright, thank you. I’m going to take him inside. Send Dr. Nestor in when she gets here, please.”

Grillby shepherds him gently into his house, flicking the lights on and guiding Gaster to sit on the couch. He wraps a fleece blanket around Gaster’s shoulders, then vanishes for a (very nerve-wracking) moment before returning with gloves and a damp washcloth. Gaster tries his very best to hold still while Grillby wipes his injury off—the washcloth comes back sticky and red. “What is this?” Grillby asks, a frown flickering across his face. “Blood? Did they get to the marrow? Wings, that’s bad.”

“I know,” Gaster murmurs. He brings a hand up, resting it over the vertebrae of his neck. “I guess it has to be. I don’t know where else blood would come from.”

“Fuck,” Grillby says, quietly, but with lots of Feeling. Gaster appreciates that. “What’s on your mouth? More blood?”

“I bit them."

“Good boy.”

Gaster has to preen a little bit, at that. Grillby hands him the washcloth, and he scrubs the blood his magic hasn’t dissolved from his teeth and jaw. “Ew,” he says despondently.

“Yeah, I don’t imagine it tastes good. How did they hurt you?” Grillby gently catches his chin, guiding it to the side so he can see Gaster’s neck, just as the monster had done—Gaster cringes and pulls back. Grillby lets him, making an apologetic noise low in his throat.

“They bit me.”

“Ah. Gross.”

“Yeah. That’s how I felt.”

“I’m sorry. I wish that hadn’t happened. I should have been there more quickly, I—”

“Hey, no.” Gaster reaches out to cup Grillby’s face in his hands, bonking their foreheads together. “It’s not your fault. Don’t blame yourself or I’ll be mad.”

A weary smile flickers across Grillby’s mouth. “Okay.”

“Thanks for coming, by the way. You’ve always got my back, huh?”

This time Grillby’s smile feels a little more genuine. He reaches out, squeezing Gaster’s hand. “Always.”

There’s a gentle knock on the door, and the both of them glance over, their eyes narrowing. Grillby moves to usher Dr. Nestor into the house, speaking quietly with her for a moment. When they reach the living room, Grillby leans against the far wall, folding his arms across his chest and watching the scene quietly. Dr. Nestor comes to sit beside Gaster on the couch, setting her medical kit at her feet.

“Well, good evening, Dr. Gaster,” she says, tugging on a pair of pink nitrile gloves. “I’m sorry we had to meet on such unpleasant terms.”

“On the bright side, they could be more unpleasant,” Gaster offers.

“That they could, that they could. So what kind of injuries are we looking at?”

Gaster gestures first at his neck, then at his right hand. “Puncture wounds and fractures, that’s all. Nothing life-threatening.”

“Alright. Well, we’ll get those taken care of, and then I’ll give the rest of you a once-over just to make sure that’s all there is. With all of the adrenaline, you may have missed something.”

“So I’ve been told.”

“May I see your hand?”

Gaster holds out his right hand, and Dr. Nestor takes it, cradling it gently in her own and examining the thin fractures at the far edges of his metacarpals. “Not too bad, not too bad,” she says. “You know, skeletons really do make things easier—no x-rays for you!”

“Way to look on the bright side,” Gaster says, a wry smile on his face. Talking like this, in his own living room, with lights and familiar faces and safe smells, feels...normal. It feels better. His fear has begun to wane, and in its absence, weariness surges in. He wants nothing more than to curl up and breathe for several hours, and that’s exactly what he plans to do, once Dr. Nestor and the guards have gone. “So what’s the fix?”

“Well, it’s only your second metacarpal you’ve fractured,” Dr. Nestor says, rummaging through her medical kit with her free hand. “Since we don’t have any swelling to worry about, I’m going to go ahead and buddy cast it. That’ll keep it immobile while it heals. To keep the pain down, I recommend ice packs and ibuprofen. If that doesn’t work, call me at the hospital tomorrow and let me know, and I can write you a prescription for something stronger. I think you’ll be A-okay, though. This isn’t too bad.”

She pulls a package of alcohol wipes from her bag, gently rubbing one across the fracture in Gaster’s hand. “Sorry, sorry,” she says when he hisses at the sting, but compared to everything _else_ he’s felt tonight, that pain is nothing. “There we go, all done. You want a lollipop?”

“Are you patronizing me?”

“Just a little.” She pats his hand, then shows him the black hand brace before she begins to velcro it into place. “This part goes around your palm and wrist, and this part is going to hold your first and second fingers together. Keep it on as much as possible. You can take it off to ice it and shower, but that’s it. Make sure you keep that fracture clean, too. A bone infection is nothing we wanna mess with. Deal?”

“Deal, Doctor.”

“I want you to come see me in about a week, so we can make sure everything is healing the way it should. I’ll have one of our receptionists call you tomorrow to make an appointment. Let’s take a look at those puncture wounds, now, please.” She reaches for his chin, and he winces, his eyes darting skittishly towards Grillby. 

“It’s alright,” Grillby soothes, coming to sit on his other side. “Here, will you let me?”

Grillby gently takes his chin, and this time, Gaster allows his head to be turned to the side. Unpleasant it may be, but he knows it’s necessary, and fighting is only going to make him feel a fool. 

“I’ll be gentle,” Dr. Nestor assures him, and he hears her rummaging through her bag again. He fights against the urge to look back at her, curiosity (and fear) biting hard at his sternum. “You just let me know if you need to stop and we’ll take a break. I’m going to take a quick peek, flush the wounds with saline, spray in a little antiseptic, and wrap ‘em up nice and neat for you. Alright?”

Gaster nods—well. He nods as much as he can nod when his face is in Grillby’s hands, anyhow. “Alright.”

Gentle, cold fingers ghost around his wound, though they take care not to touch it. After a moment, Dr. Nestor’s hands retreat again. “I’m going to flush them now, Dr. Gaster. Hold as still as you can for me.”

He squeezes his eyes shut as she places a syringe against the first puncture wound, then forces in a stream of warm saline. It stings, and he can’t quite keep from jolting, but Grillby’s hands hold him firmly in place. He reaches up, curling his fingers around Grillby’s forearm and sucking in a miserable, shaky breath. Grillby crackles sympathetically at him, smoothing a thumb across his cheek. Dr. Nestor repeats the process with the second puncture, then sits back again, clapping her hands. 

“There we go,” she says cheerfully. “Awesome job, doc. I’m just gonna disinfect and bandage them now.”

He hears the rattle of a spray bottle being shaken, and then his neck is coated in cold antiseptic. It stings, and he clicks his teeth unhappily. Once it dries, Dr. Nestor winds a clean white bandage around his vertebrae and tapes it in place.

“I’m just gonna take a quick peek rest of you, and then I promise I’ll leave you alone,” Dr. Nestor says. She lifts his shirt, glancing over his ribs and spine, then runs her palms along his hips and legs, feeling for any cracks or displacement. “No pain anywhere else, Dr. Gaster?” He shakes his head. “Theeen we’re all done!”

Gaster breathes a sigh of relief, and Grillby releases his chin after murmuring a quiet, “Well done, love.”

Then, because _fuck decency_ he’s _miserable,_ Gaster climbs into Grillby’s lap and settles quite comfortably there. Warm arms close around him, and he peers back at Dr. Nestor. “I was led to believe,” he says, “there would be a lollipop involved at this point in time.”

Dr. Nestor laughs, digging through her bag and pulling out a cherry sucker. “How’s this?”

“Good.” He takes it and unwraps it, popping it into his mouth and beginning to gnaw. Mm, sugar. What bliss. (It does a good deal to mask the damp, musky flavor of blood caught between his incisors.) “Thank you.”

“You’re more than welcome. I’ll see you in a week, alright? Call me if you have any questions, or if anything changes.” Dr. Nestor packs her bag, then heads for the door. “I’ll send the Guard in for a short— _short—_ statement, and then you both need to rest.”

As promised, a member of the Guard slips into the living room a few minutes later. They sit down next to Gaster, whip their notepad out, and scribble furiously as he tells them what happened. It’s an easier story to tell, now that he’s not trembling and half-sick with distress, and Grillby listens as intently as the guard does when he speaks. Once he and Grillby have both given their statements, the guard wishes them well and begins to gather their things.

“Wings?” Grillby asks. “Do you want me to stay the night?”

Gaster is nodding before the third word is out. “I’ll meet you upstairs in just a moment.”

As Grillby heads for the bedroom, Gaster follows the guard to the door. “Yes, Dr. Gaster?” they ask, peering curiously at him as they button their coat into place. 

“I know you aren’t the one who makes the final Judgement,” Gaster says, “but I just wanted to ask your general impression—do you think Grillby will be in trouble for this?”

The guard’s eyebrows arch in surprise. “Mr. Grillby? Why, no. If anything, he’ll be commended. From what I’ve heard, he acted solely in your defense—and a well-deserved defense it was. That monster had intent to hurt, if not to kill. Besides, he’s an elemental.”

Confusion flickers across Gaster’s face. “An elemental?”

“Yes—Mr. Grillby, I mean, not the perpetrator.”

“Yes, yes, I know who you meant. I just don’t see what his species has to do with it.”

“Oh, well, you know how it is,” the guard says, a tad apologetically. “You can’t very well fault an elemental for reacting more, er, violently than another species would. Born and bred for fighting, they are—and Mr. Grillby especially! An old warsoul, that one. Killing an enemy must have been the most natural thing in the world for him, and easy, to boot. Hell, he might not have noticed he’d done it until too late. Wouldn’t have taken much, with his LV.”

“Right,” Gaster says quietly. The air tastes bitter between his teeth. “Of course. Well—have a good night.”

“You too, doc. We’ll be in touch with you about the court proceedings, so keep an ear out, and be safe!”

Gaster shuts the door behind them, clicking the lock shut and sighing. He trudges upstairs, locking that door behind him, too, before collapsing into bed next to Grillby. One warm hand smooths over his skull, and he flips onto his side and burrows up against his soulmate. “Hey,” he says softly. 

“Hey,” Grillby says. “What’s up?”

“Did you mean to kill them?”

Grillby hums, glancing up at the ceiling. For a moment, he’s quiet. Then: “I acted in the heat of the moment, so it wasn’t a conscious decision. I didn’t want to kill them, I just wanted them to stop hurting you, and I suppose my attack was stronger than it needed to be. I’m not upset that I did it, though. I’ve killed people for far less honorable reasons.”

Gaster winces.

“What?” Grillby asks. “Are you upset with me?”

“No, no, nothing like that. You’re right. I know it’s hard for you to manage your attacks—you’re just too powerful, huh, big guy?” A halfhearted smile flickers across Gaster’s face, and then he groans, sitting up. He rests one palm against Grillby’s chest. “Can I?”

“Always.”

Gaster summons his soul—it’s a tattered thing, full of cracks and ridges and dark blemishes. He brushes his fingers over it, and Grillby lets out a quiet breath, his eyes closing. His magic curls lovingly against Gaster’s fingers, warm and bright and steady. This close, Gaster can practically taste Grillby’s emotions: confusion and uncertainty (is Wings mad at him? is he really? Grillby didn’t mean to make him mad, he really really didn’t—), the sour remnants of fear (he thought Wings was going to die, _he thought Wings was dying,_ when he heard that _scream—_ fuck, he never ever wants to hear that sound again), the faded prickle of anger (how dare anyone _hurt his soulmate)._ Beneath all of that, though, there’s a soft, familiar emotion. It burns vivid and sugar-sweet, coiling warmly against Gaster’s palm.

“Yeah,” he whispers to his little warsoul. “I love you too.”

After a moment, the soul flickers away again. Grillby opens his eyes, reaching for him. He tugs Gaster down, and Gaster settles against him, his cheek pressed to Grillby’s chest. He can feel the thrum of his soul through his body, a distant drumbeat. “Rest,” Grillby says. “I’ll be here when you wake up.”

“Need to get up early,” Gaster murmurs, his eyes drifting shut. “Get _something_ done on those papers before my meeting.”

Grillby laughs. “Oh, Wings. You’re rescheduling.”

Gaster thinks about bristling, about digging in and fighting, but right now—right now, it’s so much easier to just let Grillby make sense. “Yeah,” he agrees, instead. “Okay.”

It is one of the last times agreeing with Grillby is going to be _easy._


	2. chicken noodle soup

**Notes for the Chapter:**

> warnings: illness, nausea and vomiting, unhealthy coping mechanisms, symptoms of acute stress disorder

Gaster drops a handful of chopped celery into a pot of simmering chicken stock, then steps back and eyes his brew critically. “Almost done with those carrots?”

“Almost,” Grillby says. The rhythmic chop-chop-chop of his knife against his cutting board hasn’t faltered once in the last five minutes, and Gaster is suitably impressed. After one final, elegant chop, Grillby sets his knife aside and presents Gaster with a board full of evenly-sliced carrots. “Ta-da.”

Gaster claps his hands, albeit gently. His right hand has been healing well, but it’s still sore, and he’s in no mood to whack it the wrong way and deal with the incessant, painful throbbing that would inevitably follow. “Awesome, so now we just need—ah, ah, ah, you sit your fine ass back down right this second, mister!”

Grillby, who had been moving to bring him the carrots, flops back down onto the couch with a barely-restrained whine. “Wings, come _on._ Sitting here makes me feel useless.”

“You’re already being more useful than I want you to be,” Gaster points out, snatching the cutting board from his soulmate before he can get any other funny ideas. He slides the carrots into the chicken broth, then returns the board to Grillby, along with a red onion. “You need to be resting, not doing housework. That’s what I’m for today, okay?”

“It doesn’t feel fair.”

“It’s not, and that’s okay,” Gaster says. “Not everything has to be fair all the time, Grillbz. We’re not keeping score. Learn to take a little.”

This time Grillby doesn’t bother restraining his whine at all. He slides down the couch, pouting at his onion and at Gaster in turns. “It makes me feel bad.”

“Don’t feel bad.”

“Easier said than done.”

“Hey.” Gaster slides the lid back onto the soup pot to let it simmer, then puts his hands on his hips and looks back at Grillby. “I _like_ taking care of you. I like knowing that you’re resting and recovering instead of working yourself into the ground, and I like feeling useful. You deserve to be cared for, and I want to do this for you, so you really don’t need to feel guilty. Besides, this is what we’ve always done, right? We look after each other, no matter what—so let me do my job and look after you already.”

Grillby flickers in soft, adoring colors—golds and whites and dashes of pale pink. Gaster feels warm all the way through. “You’re doing a great job,” Grillby offers, “for what it’s worth.”

A smile dances across his face. “Thank you, lovie.”

“I know I don’t make it easy. I’m sorry.”

“That’s okay.” He ambles into the living room, leaning down to kiss Grillby’s nose. “Practice makes perfect.”

“If it’s all the same to you, I’d rather practice a little less.”

Gaster laughs. “I can understand that. How are you feeling? Any better?”

“A little. I think the medicine’s finally kicking in,” Grillby says. He follows this statement up with a hoarse, grating cough that has Gaster wincing. He takes a seat next to Grillby and rubs his back in slow circles until his breathing evens out again. “Ugh. I take it back. Gods, this sucks.”

“I know,” Gaster says sympathetically. Grillby leans against him—lightly at first, and then move heavily as Gaster pulls him closer. “Poor thing. Are you still cold?”

Grillby nods, tucking his head against Gaster’s shoulder.

“Maybe we should head to Hotland.”

“Nooo. ‘s too far.”

“Will you drink some butane, at least?”

Grillby makes a face. 

“I know you don’t like it, but it’ll make you feel better. C’mon.” Gaster ruffles the flames atop Grillby’s head gently. “For me? Can’t my big, brave monster do this for me?”

Grillby sniffs unhappily. “That’s manipulative.”

“Mm-hm. Needs must.” Gaster stands, ignoring Grillby’s pathetic whine as he does. (Although _stars_ can Grillby sound heart-breaking when he wants to. It’s like ignoring a puppy. Gaster won’t be able to manage it long.) He heads for the kitchen, perusing the variety of flammable liquids at his disposal. He snags the bottle of butane—clean and strong and just what Grillby needs, at the moment. When he returns, Grillby looks sulkily at him. 

“Gross,” he says, but he accepts the bottle when Gaster offers it. 

“I know it is. Just chug it.” He reaches for the cutting board, pulling it off of Grillby’s lap and into his own as he takes a seat. Grillby takes a deep breath, steeling himself, and Gaster begins to peel the onion. “Okay. One, two, three, go.”

Grillby fits the bottle to his mouth, then tips it back and swallows several long draughts before tearing it away and hissing out a mouthful of white smoke. 

“There you go,” Gaster says, nudging him affectionately. “Good job.”

Translucent blue flames curl from Grillby’s chest outwards, little streamers of color racing along his arms and shoulders and face. The temperature around him spikes noticeably, and Gaster hums in approval as he begins to chop the onion.

“That is,” Grillby says, setting the butane aside, “just as disgusting as I remember.”

“But do you feel better?”

He crackles quietly for a moment, then nods. “Warmer.”

Gaster beams. As soon as he’s finished chopping the onion, he dumps it into the still-simmering broth on the stovetop. He tosses in a handful of spices next—salt, pepper, thyme, parsley, garlic powder, and (at Grillby’s request) cayenne. The result is a chicken noodle soup stong enough to make his eyes sting. Once the vegetables have softened, he ladles quite a bit of the soup into a bowl and offers it to Grillby.

“Thank you,” Grillby says, cradling the bowl between his palms. “It smells wonderful.”

“Well, let’s hope it tastes as good as it smells.” Gaster readjusts the heating blanket around Grillby’s shoulders, then leans down to kiss his temple. “Eat up. There’s plenty more, and stars know you need the energy.”

As Grillby begins to eat, Gaster serves himself a bowl and eats quickly, and in sharp little bites, because holy _fuck_ the cayenne is strong. Still, he isn’t quick enough. By the time he’s chasing one final, soggy noodle around the bowl with a spoon, Grillby is tipping the last of the broth into his mouth and looking hopefully at him for more. Gaster serves him his seconds, then leans back against the kitchen counter with a sigh of satisfaction. He may not be quite the chef Grillby is, but it’s still nice to be able to make something for someone, to be able to sustain them with something _he_ prepared. 

“Good?” he asks, as Grillby scrapes his second bowl clean.

“Wonderful,” Grillby says, looking warmly at him. “I need to let you cook for me more often.”

“Ha!” Gaster’s cheeks flush, and he ducks his head. “It’s just you rubbing off on me.”

Grillby holds out his bowl. “Encore, chef?”

How can Gaster say no to that _face?_ He fetches Grillby a third bowl, then curls up in his lap and takes a peek at the TV—they’re watching an old black and white film he recognizes but can’t quite name. Grillby rests his bowl on Gaster’s shoulder as he eats. “What’s this?” he asks.

 _“Nosferatu,”_ Grillby says. “From 1922, back when they were still making silent films. It’s not great, but I remember watching it when it first came out. Kind of nostalgic.”

“Huh.” He settles in to watch the ending of the movie, listening quietly to the clink of Grillby’s spoon as he eats. “Anything else you need?”

Grillby remains quiet for a moment. Then, his tone of voice almost shy, he asks, “Can you purr?”

Gaster’s smile stretches from (metaphorical) ear to ear. It isn’t a difficult thing to do at all—not when he’s this warm and safe and happy. His purr rattles to life in his ribcage, warbly and rough, and Grillby pats him gratefully. A song pops into Gaster’s head, then, and it’s simply too good to resist, even though he has to choke off his purr to speak. “Wait wait wait—you know that song, Grillbz? That one that goes like, ‘I'm pickin' up good vibrations, she's giving me the excitations—’”

Grillby laughs, his flames sparking with delight. “Oh my god, stop.”

Gaster bobs his head along to the beat in his mind, grinning. “‘Gotta keep those lovin' good vibrations a-happenin'. Good, good, good, good vibrations, she's giving me the excitations, and I'm pickin' up good vibrations—’”

Grillby pushes forward, puts their face inches from each other, and whispers very seriously, “You are ridiculous.”

Gaster laughs and kisses him.

“The Beach Boys!” he exclaims into their kiss, when the right artist hits him. “‘Good Vibrations’ by the Beach Boys, that’s it.”

“You’re my favorite,” Grillby says, and then kisses him some more. Gaster has no complaints to make, and when his purr starts up again, it feels like the most natural thing in the world. He falls asleep there in Grillby’s lap, listening to the soundtrack of soup, fire crackling, and his own purring. He expects to wake feeling well-rested and content, as he usually does when he naps with Grillby, but this time that’s not the case. 

This time, he wakes up and he feels _weird._

First of all, he’s _cold,_ which happens very rarely when he’s around Grillby. His joints ache with the chill, and he shifts, glancing up just to, you know, make sure Grillby’s still here. He is—he’s napping, too, an empty soup bowl balanced precariously in one hand and his head tipped back against the couch’s headrest. That can’t be comfortable. His flames burn low in his sleep, but they shouldn’t be burning low enough for Gaster to chill. He holds his palm out, a few inches from Grillby’s bare chest, and feels the warm lick of his soulmate’s flames. That feels normal, at least. He’s just not sure why that heat isn’t soaking into his bones the way it usually does.

Gaster sits up stiffly, careful not to wake up Grillby, and aches twinge through him. Blegh. Gods, is he _sick?_ Has he caught whatever bug Grillby has? That shouldn’t be possible, seeing as they’re different species, but Gaster’s come to realize that very few things in this world are legitimately impossible. He rubs his eyesockets with a balled-up fist, sighing heavily. When he can muster the energy to stand, he gathers up Grillby’s dishes and takes them to the sink. Then he guides Grillby into a more comfortable position on the couch, draping the heating blanket across him and tucking him in. Grillby murmurs quietly in his sleep, and Gaster smooths a hand through his flames, hushing him softly.

Then he straightens up, and a wave of nausea crashes over him and cramps his soul into a debilitating _twist._ His breath hitches, and he gulps desperately as he stumbles into the bathroom. He lowers himself to his knees, huddles up against the toilet, and then proceeds to retch up what feels like half of his goddamn magic. _Fuck,_ that is unpleasant. As soon as he’s done, he sits back, fumbling to grab the hand towel next to the sink and wiping his teeth clean. 

“Wings?”

He nearly jumps out of his own bones, whipping around to see Grillby standing sleepily behind him. A worried yellow tint streaks through his flames, and his brow furrows.

“Sorry,” he says. “Didn’t mean to scare you. Are you okay?”

“I think I’m sick.”

“Well, damn.” Grillby kneels beside him, reaching to rest one hand on his shoulder. “This kind of sucks, huh? But at least we can be sick together.”

“Yay,” Gaster says bleakly. “Bonding time.”

“Don’t look so thrilled. C’mere.” Grillby takes a seat on the bathroom floor, opening his arms, and Gaster squirms into them. “Did you throw up?”

“Mm-hm.”

Grillby hums sympathetically, smoothing a hand over his spine. “I’m sorry, Wings. On the bright side, it doesn’t feel like you have a fever. Actually, you feel colder than usual.”

“I am cold,” Gaster admits, pressing his face to Grillby’s collar. Grillby’s flames brighten, the air around them warming significantly. “Thank you. You should save your energy, though.”

“Why don’t you come cuddle under the blankets with me, then?”

“I might throw up again.”

“I’ll grab the trash can.”

Gaster reluctantly heaves himself to his feet, stumbling back into the living room. He burrows underneath the heating blanket, breathing in the smokey scent Grillby has left behind. When Grillby joins him, he carries a trash can, a medicine cup filled with pink goo, and a bottle of water. He takes a seat next to Gaster, handing him the water before resting a hand on the small of his back. 

“I brought some medicine to help with the nausea,” he says, “if you think you can keep it down.”

“I can try.” 

“That’s my boy.”

Gaster reaches for the medicine cup, downs the pink goo with a gulp of water and a grimace, and then shoves his face back into the couch cushions. Grillby squeezes the back of his neck gently, then whisks away the medicine cup before curling up next to him. They sleep more, after that—or at the very least _Gaster_ sleeps more. It’s a fitful sort of sleep, and he wakes up several times to vomit. Each time, Grillby sits and comforts him through it, then lulls him back to sleep with soft touches and quietly-hummed lullabies.

By late evening, Gaster feels a little bit better—although that could be, he supposes, because his body has literally nothing left to retch up. He refuses the food Grillby offers him, and Grillby reluctantly finishes off the last of chicken noodle soup by himself. After that, they settle in to watch a history documentary on some human war Gaster can’t be bothered to care about. He rests his head in Grillby’s lap, and Grillby pets him gently. He’s pleased to notice that Grillby’s breathing seems to have cleared some, and his coughs come less frequently. At the very least, one of them is on the mend.

Gaster spends the night at Grillby’s, and when he wakes, he doesn’t feel half bad. He doesn’t feel _good_ by any means, but he isn’t awful. His joints are still sore, and his energy has plummeted—though that is, no doubt, what he deserves for eating nothing all day. Tiny shivers rack his frame, so he keeps the heating blanket bundled around his shoulders as he makes his way to the kitchen. Grillby already has pancakes waiting for him, and he beams and nuzzles up to his soulmate and says his thanks through flurries of kisses that have Grillby giggling and batting him away. 

“Sit down, sit down, eat,” Grillby says, shooing him towards the table. “Slowly. Don’t push yourself.”

Gaster pokes the pancakes tentatively. They’re crispy at the edges, already smothered in syrup, just the way he likes them. He saws off a small piece, then jams it into his mouth. Heaven. The edge has a perfect crunch, while the center is fluffy and subtly sweet. The syrup sticks to his teeth before dissolving in a rush of sugar, and he can _juuust_ taste the delicate snap of salt from the butter. He moans in delight, already sawing off another bite.

“‘s hard to eat slow,” he says, swallowing hastily, “when you make such good food.”

Grillby points his mixing spoon warningly in Gaster’s direction. “If you eat too fast and make yourself sick, you’re getting vegetables for lunch.”

Gaster eats too fast and makes himself sick and he does, in fact, get vegetables a few hours later for lunch. He whines when he does, poking a green bean unenthusiastically. It’s prepared as lovingly as any of Grillby’s other dishes, basted in bacon grease (very lightly, because Grillby insists they don’t need to overwhelm Gaster’s palate when he’s already ill) and speckled with garlic, but it’s still a _vegetable._ Even Grillby can’t make that fact disappear. “Grillbyyyyy.”

“Yes, dear?”

“Can’t I have a pancake?”

“Try eating that first. It’s better for you, and not as heavy as the pancakes were.”

“I don’t like it.”

“You haven’t even tried it.”

“It’s a vegetable.”

“Technically it’s a fruit.”

“It’s a what.”

“A fruit. It has seeds, it’s a plant’s reproductive organ, it’s a fruit. Didn’t you know that? You’re a scientist.”

“I’m a _physicist,_ not a _botanist._ You’re telling me green beans are _fruits?”_

Grillby laughs. “Yeah, I am—so quit complaining and eat it, already.”

Gaster doesn’t quit complaining, but he does eat, and a good deal more slowly than he ate his breakfast, which was the whole point. Despite that, his soul still begins to turn queasily. 

“There,” Grillby says, whisking away his plate. “Was that so bad?”

Gaster swallows hard, shaking his head before he realizes Grillby is still turned away from him.

“Wings?” Grillby peers back, concerned. His face falls when he sees Gaster’s expression and the tentative way he holds himself. “Oh, sweetheart. Do you need the trash can?”

Gaster nods quickly, and then spends the next few minutes retching unhappily. Grillby smooths a hand across his skull, frowning. “Oh my gods,” Gaster gasps, once he’s finished his regularly-scheduled vomiting. “I am so done with this.”

“We’ll try something lighter next time,” Grillby says, although there’s a worried frown on his face.

“I don’t want to eat anything ever again in my _life.”_

“I know, I know, but you have to keep something down or you’ll get sicker. How about some toast and applesauce?”

Gaster sighs forlornly. “If I must.”

He _does_ manage to keep the toast and applesauce down, although it’s a fight. He lays very, very still after he eats it, and he can’t say he feels any better for having done so. It seems to bring Grillby relief, though. It’s enough of an improvement, at least, to let Gaster convince Grillby to go back to work at the bar the next day.

“I’ll be _fine,”_ he insists when Grillby tries to balk. “I’m feeling a lot better. I’ll take tomorrow off from the lab, but there’s no reason you need to stay home and baby me. I know you. You’re gonna go stir-crazy if you have to potter around here any longer.”

“Maybe,” Grillby agrees, albeit grudgingly. “You’ll call me if you need me, though?”

“Right away.”

“Good. I’ll walk you home tomorrow.”

Gaster laces his fingers with Grillby’s and gives them a squeeze. After what happened _last_ time he left Grillby’s alone, he doesn’t much mind that idea. “My gentleman.”

Grillby walks him home early the next morning and bundles him in blankets on the couch, arming him with the TV remote and a plate of warm toast smothered in peanut butter. “Get to feeling better,” he says, kissing Gaster’s temple. “I’ll call you tonight.”

“Thank youuu.” Gaster tips his head back into the kiss, smiling. “I love you. Have a good day at work.”

“I will—and I love you too, of course.”

Once Grillby has gone, Gaster takes a few tentative bites of the toast. When his soul cramps, he grimaces and tosses the rest of it out. He does the same with his lunch and dinner. It worries him to do so, but he just _knows_ he won’t be able to keep it down. Besides, he can still keep water down, so he’s not in imminent danger if he goes without a few meals. Right now, the lack of food just makes him feel slow and groggy, and he can handle that—but when a week and a half has gone by with him subsisting on little more than crackers and the occasional ambitious banana, he gets nervous. 

He knows, logically, that he should tell Grillby he’s still sick. They’re _soulmates,_ for gods’ sake. Their lives are intricately bound, and this is—well, it’s not a _big_ problem, but it’s certainly turning into a persistent one. The thing is, he knows Grillby would bend over backwards to make him feel better, and _that’s_ the problem. Grillby has his own life to lead, and Gaster hates pulling him away from that. Now, it’s one thing to have Grillby fuss over him for a few days. He _likes_ it when Grillby fusses over him, and he knows himself well enough to admit it. Something like this, though? Something that could plague him for _weeks?_ He couldn’t tie Grillby down for that long, not when Gaster is more than capable of handling this himself. It wouldn’t be fair to Grillby.

...unfortunately, it’s also not fair to keep secrets from him like this. It wretches Gaster with guilt, and he _hates_ it. He hates the way he stops eating at Grillby’s. He hates the way he starts avoiding the bar. He hates the way he smiles and laughs and kisses Grillby like absolutely nothing is wrong and he hates how he avoids the concern in Grillby’s gaze when he turns down a dinner date. There’s no way he can do this for long, so he determines to fix it as quickly as possible. His first step is to visit Dr. Nestor at the hospital. His vitals all come back normal, but his soul, when he allows her to summon it, presents a very unhappy picture.

“Well,” he says, when he sees how faded and thin his magic has grown. “Shit.”

“I agree,” Dr. Nestor says, worry creasing her face. “You need more magic, Dr. Gaster. You need energy. You’re not getting it from food, so we can try knocking out your nausea and seeing if that helps—but treating nausea is only treating a symptom. I’m still not sure what the underlying cause here is. There’s no infection present, all your wounds are healing well, there’s no fever or abnormal cell growth or strenuous activity. Are you distressed?”

Oh, yes, very much so. “I—didn’t think? Not much?”

Her eyes soften some. “Listen. Maybe you ought to talk to a therapist about what happened with the attack a couple of weeks ago. The stress might be affecting your appetite more than you think. You know how sensitive monster souls are. In the meantime, I’ll give you some high-energy shakes to try, since you have better luck keeping liquids down. I’ll also prescribe you some Zofran to try and prevent some of that nausea. How’s that sound?”

“Good,” Gaster says, relief curling through his soul. A solution! Albeit a rocky one, but—but still! “Thank you very much.”

“It’s no problem. Look into that therapy, let me know if it helps. If not, we may need to run some more tests. If you still can’t keep food down in the next few days, call me. We don’t need your soul getting thinner than it already is.”

“Got it.”

He goes home with a packet of chocolate nutrition shakes (they were out of the peanut butter flavor, which is a _crime)_ and a bottle of pills. He manages to keep both the pills and the shakes down, and by the _gods_ does it make a difference. He starts to feel more energetic, the aches and pains that have plagued him wane, and his enthusiasm returns. Grillby notices the difference immediately, in spite of the fact Gaster had been, ah, not extremely honest with him these last couple of weeks.

“You’re chipper today,” he says when he comes to visit Gaster that night. “What gives?”

“Nothing,” Gaster says, but he can’t quite quit grinning. “Just thinking about how much I love you.”

Grillby arches an eyebrow. “Is that right?”

“Mm-hm. I love you thiiiiiis much!” He spreads his arms, and Grillby wraps him up in a hug and spins him around, peppering his face with kisses and little licks of flame.

In the meantime, Gaster _does_ consider going to therapy, as Dr. Nestor had recommended, but ultimately decides against it. After all, he feels perfectly fine, now! Maybe he just needed a little pick-me-up for things to settle back down. He doesn’t doubt he _was_ stressed about what happened—who _wouldn’t_ be stressed about being attacked by a stranger outside of your own home? Fortunately, he hasn’t noticed any lasting effects, now that the nausea has been dealt with. He’s fine. He is _perfectly_ fine.

Three days of chocolate shakes and pills later, he finds himself retching over the toilet again.

“Fuck,” he whispers to the toilet. It doesn’t respond, but he imagines it feels sympathetic to his plight, anyway. “Do we need therapy?”

But nothing else is _wrong!_ If it’s a psychological trauma, shouldn’t there be other symptoms? Flashbacks, or nightmares, or—or jumpiness? Well, sure, he gets a little nervous outside at night, but that’s just rational. The night is a nerve-wracking thing. And he’s had nightmares, but nothing concrete, nothing specifically about being pinned down and bitten and having his soul _torn._ Everyone has nightmares that leave them shaky and uneasy, sometimes. He doesn’t need therapy. He just doesn’t. That’s being silly.

The next morning, he wakes up with a throbbing toothache. “If this is a psychological trauma,” he whispers to his toilet during his regular breakfast vomiting, “it is presenting itself in a _most ridiculous_ fashion.”

To the dentist he goes. One panoramic x-ray later, Dr. Cho pronounces him fine and dandy. “Everything looks great, Dr. Gaster,” she says, showing him his x-rays. “Tooth density all looks phenomenal, roots are in great shape, there aren’t any cavities that I can see—keep up the good brushing and flossing work. Now, which tooth did you say was bothering you?”

“This one.” Gaster points at his right eyetooth.

“Well, let’s lean you back and I’ll take a closer look.” She pokes and prods at his tooth with her little tools and mirrors, her ears pricked. “I’ve gotta say, it looks like a perfectly healthy chomper to me—nice and sharp. Now, you’ve got a filling in it, but you’ve had that for years. It shouldn’t be bothering you now; it’s far too early for it to be replaced. The surrounding socket is healthy, and the tooth isn’t loose at all.”

“So what you’re saying is it’s all in my head?”

“Well, all your teeth are you in your head, silly,” she says, putting her tools away. “But physically, there’s nothing wrong. Try icing that tooth, if it keeps bothering you, and take some ibuprofen. If it’s still hurting in about a month, come back and we’ll look again. It shouldn’t be bothering you if nothing is wrong.”

His toothache doesn’t fade. If anything, it gets worse throughout the next week, growing to encompass most of his upper jaw. That, along with the lack of food, makes him crankier and crankier. He spends most of his evenings sulking and chewing on ice, because the pressure feels good against his sore teeth and the liquid soothes his thinning magic, although it offers no nutrition. He’s lucky if he can keep anything of any value down for more than five minutes.

It isn’t surprising when Grillby mentions something. His illness grows harder to hide with each passing day, and he’s forced to wonder why he even bothers hiding it anymore. It’s certainly something worth talking about, now, but that damned _habit_ is coming back to bite him. (“Another psychological symptom?” he suggests to his toilet, during one of their many vomiting sessions.) He and Grillby had fought tooth and nail to break Gaster’s nasty little habit of hiding his problems—that hiding act had made Gaster feel safe for many, many years. He was only able to quit once he realized Grillby made him feel even safer.

So why doesn’t he feel that way now? Why is his guilt suddenly overriding years of trust and teamwork? Stars, maybe he does need therapy. He can tolerate something if it’s affecting _his_ life, but when it starts affecting his relationship with Grillby? That’s when things become intolerable.

“You don’t look good,” Grillby says, one day, which is something Grillby never ever says to him ever.

“Way to break an old man down easy, chief.” Gaster swirls his coffee in his mug, draping himself across the kitchen table.

“I don’t mean it that way. You’re handsome as ever.” Grillby swoops in for a quick kiss, which Gaster gratefully returns. “But you look tired. Your eyelights have been dim. You’re not eating. When’s the last time I cooked for you?”

“I—it’s my teeth,” Gaster admits, which is half of the truth.

“Your teeth?”

“Yeah. They’ve been hurting. I already went to the dentist and she says I’m in sound health, so—” He shrugs helplessly. “I don’t know.”

“I can make you something soft.” Grillby looks at him so _earnestly,_ so _lovingly,_ Gaster could weep. “Anything you want.”

“Soup?” Gaster suggests. It will hurt less coming back up. “Chicken noodle soup?”

Grillby practically glows. “Comin’ right up!”

The chicken noodle soup is phenomenal. The noodles are wonderfully al dente, the broth feels rich and warm, and the spices taste perfectly piquant—not too spicy, even though Grillby likes it better that way. Gaster tips the last of his serving into his mouth, sighing in bliss. Stars, he loves Grillby’s cooking. He’s _so upset_ he can’t enjoy it without dreading what comes after. “Wonderful, sparks,” he says, reaching out to catch Grillby’s hand and give it a gentle squeeze. “Thank you. Really.”

“They do look different.”

Gaster blinks. “What?”

“Your teeth. They look different.” He bends down, cupping Gaster’s face in one hand and peering closely at his teeth. “Your smile’s not the same as it was.”

“Is that a bad thing?” Gaster asks, leaning into Grillby’s palm. He smells so _good,_ like smoke and warmth and magic. Gaster’s teeth ache and ache and ache.

“No. Your smile’s always been one of my favorite things, silly.” Grillby pecks the tip of his nose, and Gaster’s soul cramps with vicious, unyielding hunger. His breath hitches, and he digs his fingers into the counter. Grillby leans back, his face open and concerned. “What? Is something wrong?”

“Nuh-uh,” Gaster says, swallowing rapidly. He offers Grillby a smile and hopes it doesn’t look as shaky as it feels. “I just—you’re nice. You’re so nice.”

Grillby beams at him, although he...doesn’t look completely convinced.

“Could I get some more of that soup?” Gaster asks hopefully. Anything to get rid of the dreadful hunger in his soul, _anything._ He doesn’t care how much it’s going to sting coming up. Besides, the way Grillby lights up, thrilled, when he hears Gaster’s request—well, that in and of itself is a balm to his weary soul. He downs two more bowls of chicken noodle soup, and tries very hard not to cry when it does nothing to ease his hunger.

Then he goes home, and he retches it all back up.

When he glances in the mirror, leaning wearily against the bathroom wall, he sees what Grillby meant. His teeth _are_ different—two teeth in particular. The difference isn’t much, but it’s enough for Gaster to notice. Both eyeteeth look larger and sharper than they should be. He manifests his tongue, running it carefully along the points of his teeth. Yes, they’re definitely sharper than they were. 

He thinks of gleaming fangs in the darkness outside of his home, he thinks of being _bitten,_ and he shudders and lurches for the toilet again.

**Notes for the Chapter:**

> ooooooh gaster. oooooooh gaster u little self-loathing fool.


	3. dandelion greens

**Notes for the Chapter:**

> warnings: allusions to nsfw, references to violence/death, minor injuries, self-loathing

“So how go the Core proposals?” Grillby asks, sprinkling lime juice across a bowl full of dandelion greens. 

Gaster hums thoughtfully, carefully peeling the skin away from a grapefruit. “Oh, they’re good, they’re good. The interns have a few really lovely ideas for improvements.”

“I’m glad to hear that. How many more do you have to look over?”

“Only ten.” As soon as he’s finished the grapefruit, he offers it to Grillby. He’s dreading this meal (or, more precisely, what happens after the meal), but he could hardly avoid yet _another_ dinner date without arousing Grillby’s suspicion past the point of no return—or without making Grillby feel insecure, which is _absolutely_ something he never wants to do. “Here, this is ready.”

“Thanks. I’ll even trade you for an orange—you can go ahead and eat that it, if you want. I have enough for the salad already.”

Grillby takes the peeled grapefruit from him, pulling it into slices and tossing them into the salad. Meanwhile, Gaster peels the orange slowly, then bites into it. The pressure against his teeth is bliss. He’s tempted to gnaw harder, but that would make a mess. As he contemplates this misfortune, some sleepy instinct uncurls in the back of his mind, and he’s struck with urge to suck—so he does. He breaks the orange’s skin with his teeth, then sucks the juice out and hums happily. Flavor bursts through his mouth, bright and sweet and sharp. Gods, he’s already imagining how awful it’s going to feel coming back up. Citrus acid burns. 

“Is that how you eat your oranges now?” Grillby asks, chuckling.

“Yes. _Orange_ you glad I’m so unique?”

A grin flickers across Grillby’s face, and he carefully picks a proper slice of orange from the salad, then offers it to Gaster. “Here. Bite.”

Gaster is very much in favor of biting, please and thank you. He reaches out to hold Grillby’s wrist, taking the orange slice gently from his fingers and crushing it between his teeth. He swallows, then leans forward and manifests a tongue, licking the orange juice from Grillby’s fingers, because licking Grillby is suddenly very, very appealing. He only realizes his mistake when Grillby’s flames prickle under the damp touch, and Gaster winces and leans back.

“Sorry,” he says. “Does that hurt?”

Grillby stares at him, mouth open. When he realizes Gaster is looking, he quickly gulps and snaps it shut again. “No. I mean—not really. It’s not a bad pain.”

“Not bad, or…?”

Grillby’s flames flare delicate pink. “Good. It’s good.”

“Good, huh?” Gaster grins, leaning forward to take one of Grillby’s fingers into his mouth. He curls his tongue around it, suckling gently, and practically preens at the feeling when he does. Stars, that feels good. That feels _right._ That is absolutely what he’s supposed to be doing. Even so, his soul knots in miserable hunger, and he can’t help but whine. “Grillbyyy, I’m hungryyy.”

Grillby’s flames shiver with streamers of heated white and flustered pink. “Um. I. Yes. It’s—salad is almost done. I just have to add the onion.”

“But I’m hungry _now.”_ He’s always so _hungry._ It feels like he’s been hungry for ages; he doesn’t remember what it was like to be satisfied. He knows, logically, that whatever Grillby gives him won’t do anything to sate his hunger—but gods, he has to try, doesn’t he? He doesn’t know what else he can do. His soul cries constantly for something, _anything,_ and Grillby has always been its loving provider. “Feed me?”

Grillby shivers, leaning forward to bump their foreheads together—at the same time, he flails a hand backwards for the salad bowl. He offers Gaster a slice of grapefruit, and Gaster plucks it from his hand again, licking the juice from his fingers as a soft purr rattles to life in his chest. “Good?” he asks.

“Mm-hm.” Gaster closes his eyes, well-pleased. The food does nothing to soothe his hunger, but Grillby’s affection, at the very least, makes his soul ache a little less. “Thank you. More?”

Grillby hand-feeds him little bits of fruit and leaves—the bitterness of the grapefruit and greens are offset only slightly by the sweetness of the oranges and the sour tang of the lime dressing Grillby had so lovingly crafted. Gaster eats everything he’s offered, eyes closed and trusting. Grillby wouldn’t offer him anything bad. Grillby wouldn’t ever offer him anything bad. Grillby is a source of good things, of nutritious things, of food and _love,_ and Gaster is so so so hungry.

He catches Grillby’s hand gently, after he’s eaten several bites of the salad. He licks Grillby’s fingers clean, then mouths softly along his palm to his wrist, laving his tongue lovingly across his forearm. Has Grillby always smelled this good…? His eyes open a mere sliver, peering up at him, and _mmm,_ what a sight. His soulmate is flushed a dazzling white at the core, his eyes wide and mouth open. Gaster can just barely glimpse the black, jagged edges of his soulmate’s teeth. 

“Wings?” Grillby asks, his voice hoarse. He’s uncertain, Gaster realizes with a jolt. It’s been quite some time since they’ve been intimate this way, and that’s Gaster’s fault. He just hasn’t had the energy for it, since this damned sickness, and Grillby has been endlessly patient with him. Now, though? Now, Gaster _needs._ He’s not sure what he needs, or how to get it, but this seems like a damn good start. The last time he needed something this badly, Grillby’s lovemaking skills were quick to satisfy him. 

(He tries hard not to realize that this need feels very, very different from his usual lust. He tries very hard.)

“Is this okay?” Gaster asks. “If you don’t want to, we can stop.”

“No, this is—more than okay. But are you sure? You don’t want to eat first?”

Gaster shakes his head. “I just want you.”

Grillby crackles with affection, warm and bright, and presses a kiss to his forehead. “Then I’m all yours.”

Gaster purrs, then continues to kiss his way up Grillby’s arm, drawing him closer. Grillby leans against him, trapping him gently against the kitchen counter and sliding a knee between his legs. For some peculiar reason, that doesn’t interest Gaster much—which is saying something, because usually anything Grillby-related between his legs commands all of his attention. He loops his arms around Grillby’s neck, pulling him into a thorough kiss.

When they part, Grillby sucks in a deep breath, then slides his hands down to the small of Gaster’s back to hitch him closer, pressing their hips together. Gaster purrs his soft delight at Grillby, moving to mouth at his cheek, his jaw, his throat. He can feel his soulmate’s magic pulsing through his flames, bright and energetic and giddy. Grillby’s _happy._ Stars, Gaster wants to keep him that way forever. He rasps his tongue gently across Grillby’s neck, and then—

Well, he’s not actually sure what happens, then. He only knows that his soul cramps hard enough to leave him gasping, black dots dancing in his vision. His jaw aches, his teeth throb, and that sleepy little instinct in the back of his mind rears itself up hard and fast. He wants to bite. He wants to bite, and he wants to bite hard. He wants to bite with the intent to _hurt._

As soon as he realizes that, Gaster recoils, his eyes wide.

“Wings?” Grillby flinches in surprise at his movement, his own eyes widening as they meet Gaster’s. “Oh, woah.”

“What?” Gaster’s hands fly to his face. Oh, stars, is he turning into some kind of awful beast? What is _wrong_ with him? “What is it?”

“Your eyes. They’re red.”

“They’re _what?”_ Gaster bolts for the bathroom mirror, and his eyelights shine back at him, as red as blood. (As red as the magic that monster dragged from Gaster’s very own soul.) 

“Okay, so I know I’m not a skelemagic professional, but I’ve never seen them that color before,” Grillby says, standing uncertainly in that bathroom doorway, “and I have seen your eyes for a long time. Your eyes and I know each other quite well. So I’m, uh, a little concerned. Do _you_ know what that means?”

“No,” Gaster says, breathless with terror. He has no fucking idea what that means, and he is absolutely on the verge of freaking the fuck out about it. He thinks of the monster who attacked him, of fangs and bright red eyes, and he feels sick and scared and very, very out of control. He’s changing. He’s changing, and he hates what he’s becoming.

“Have they _ever_ been that color before?”

Gaster’s hands shake. “No.”

“Does it hurt? You flinched, earlier. Do you feel any different?”

He does. He feels so, so different—he feels cold and tired and _hungry._ He feels like he wants to do something awful. “I—I don’t—I don’t know?”

“Here, can I look at your soul?”

Gaster almost says yes, because having his soul cradled in Grillby’s hands always feels safe, and good, and _right._ Then he remembers how ugly, how thin and how miserable his soul looks, and he stumbles backwards, shaking his head. “No. Please don’t.”

“Wings.” Grillby looks at him, face creasing with confusion—and with hurt. “Is something wrong?”

“No, nothing, it’s just—I’m just—it’s fine.”

Grillby takes a deep breath, beginning to pace outside of the bathroom door. His flames jitter nervously. “Okay, let me rephrase. You are clearly not fine, so what’s wrong, and why won’t you talk to me about it? Ever since that bastard attacked you, you haven’t been acting right. You barely eat, you’re always sluggish, you have _fangs_ that you definitely did not have a month ago—oh, don’t think I haven’t noticed that’s exactly what they are—and your eyelights are dimmer than they should be. Or, wait, they’re red now! That’s not _normal._ That’s not _fine.”_

“Grillby—Grillbz, hey, come on—”

Grillby’s flames snap angrily around him. “Don’t _come on_ me. I tried to give you time, and I gave you space. I kept waiting for you to come to me. We agreed, didn’t we? We don’t lie to each other. We don’t keep secrets, especially not secrets that are affecting us _this much.”_

“It’s not a big deal,” Gaster snaps, guilt churning like tar in his ribcage. “I’m just sick, that’s all.”

Grillby falters. “Sick? You’re not telling me you’re _still_ sick?”

That was the wrong thing to say, abort abort _abort._ “I—well, it’s probably a different bug, at this point,” Gaster says, flailing for a rational answer that even he himself can’t believe. “My immune system must not have bounced back, after the first illness, and I came down with something else.”

“You’ve been sick this entire month, and you didn’t tell me?”

“I _did_ tell you,” Gaster points out, a touch vindictively. “I got sick at your house. You were there.”

“I assumed you had gotten better!”

“Well that’s on _you,_ then, isn’t it?” Gaster retorts. “I didn’t lie to you. I wouldn’t do that, not now.”

“No, you just left out some really _fucking important information,_ that’s all.” Grillby rakes his hands through his flames in frustration—frustration that Gaster very much deserves, but frustration that makes him want to bristle defensively anyhow. He’s bad at controlling his emotions in general, and even _worse_ at controlling them when he feels so—so—so out of control! It makes him want to throw up walls, to retreat and bare his teeth and drive everyone away until he feels better. “Stars. What’s gotten into you? I thought you trusted me.”

“I do!” Gaster insists, stepping forward. He takes a deep breath, trying to settle his voice some. Okay, he _isn’t_ doing this. He isn’t pushing Grillby away, not like this. Hiding is one thing, but actively lashing out? He refuses. (He’s acted horribly enough this last month _without_ adding picking fights to the list.) “I do, Grillby. I trust you. I just—I wasn’t sure it was even worth worrying about, okay? I kept thinking it would go away, I kept thinking I’d get better. I went to see Dr. Nestor and she said I was fine! Dr. Cho said the same thing when I told her about my toothache. It’s all just in my imagination.”

“This,” Grillby says, gesturing wildly to—well, all of him, “is _not_ just in your imagination, Wings, not if it’s making you act this way. Something is wrong, and we need to deal with it.”

Gaster takes a deep, shuddering breath. He doesn’t want to _deal_ with it. He doesn't even want to believe anything is _that wrong_ —but when he glances at the mirror, he doesn’t see himself, any longer. He sees the same monster that had pinned him down in the snow and tore at his soul. He sees something starved and wicked and dangerous.

“I know,” he mutters, wrapping his arms around himself. “I just—I just don’t know how to fix it. I don’t know what to do.”

“That’s okay. We’ll figure it out together, like we always do. You’ve just gotta _talk_ to me. You’ve gotta let me help.”

“I’m sorry. I’m sorry I didn’t tell you.”

“It’s okay. Er, well—it’s not, actually, and I’m kind of seriously pissed, but it can wait. I’m not going to leave you like this.” Grillby opens his arms, warm and inviting, and Gaster wants so _badly_ to go to him—but he remembers the sickness in his soul, the ache in his teeth, the urge to _bite,_ and he shrinks away. “Wings…?”

“I can’t. I’m sorry, I can’t. I feel really weird right now.”

“What are you feeling?”

Gaster swallows hard, and then he does what he goddamn well should have ages ago: he talks to his soulmate. “I’m really tired. I’ve been really tired ever since I got sick at your house. I can’t keep anything down—which, by the way, I’m gonna be throwing up that great salad you made in about half an hour and I’m so sorry because it was really good—and I’m cold all the time, and I can’t even make _attacks_ anymore, because—because look at this!”

He summons his own soul, regarding it with nothing short of disgust. It’s patched and dull, thin enough to be translucent at the edges. Honestly, he’s surprised it even holds enough magic to keep him solid. He...should have gone back to Dr. Nestor quite some time ago, but he was petrified to even acknowledge the fact that he may be creeping towards a slow death. (He was even more petrified of being told _I don’t know what’s wrong with you_ again—or, worse, _nothing’s wrong with you._ )

The horror that flickers across Grillby’s face is, he thinks, quite appropriate. The panic is not. “Oh gods,” Grillby whispers, his voice hoarse. “You’re dying.”

“I am not dying, I’m just—”

“Wings you’re dying.”

“I am _not—”_

Grillby’s flames begin to flicker in quite the uncontrolled manner, streaked with petrified yellows and whites. His breathing picks up, rough and rattling and full of smoke. His hands shake, and his eyes dart frantically behind his glasses. “We have to go to the hospital. You—fuck, that needs a _transfusion,_ how long has it been that way, how—”

“Hey, hey hey hey, easy, big guy.” Gaster wavers—he wants so badly to go to Grillby, to touch, to _comfort,_ but his fear of himself holds him rooted to his spot. If he goes over there, who’s to say he won’t do something bad? (Who’s to say he won’t do what that goddamned monster did to _him_ to start all of this?) “Let’s not freak out. This is—”

 _“This is not fine!”_ Grillby says, his voice shrill. “This is worth freaking out about, okay, fuck off. If you’ve gotten this bad in only a _month,_ we don’t have much longer. We need to figure this out right now. We are _going_ to the hospital.”

“They won’t be able to help,” Gaster argues. “I told you, I’ve already been to see Dr. Nestor, and I’m perfectly healthy, save for the whole can’t-keep-energy-inside-of-my-body thing, which, okay, yes, kind of important. But what are they going to do?”

“A transfusion!” Grillby repeats, moving forward to take his shoulders and rattle him. It is with great relief Gaster realizes the urge to bite does not return at his soulmate’s touch. “If you can’t keep food down, they’ll give you a transfusion. That will at least buy us some time.”

“Come on, it’s not that bad.”

“It is that bad,” Grillby hisses. “You just can’t see it because you’ve been too busy _ignoring_ it.”

“Alright, fine, it’s bad.” Gaster tosses his hands into the air, exasperated. “But it’s been bad for a while, so don’t go panicking now. Anyway, whatever this is, it isn’t a normal disease, or Dr. Nestor would have been able to identify it. Now, I’ve been researching rare diseases, but I haven’t found anything similar to this—and I’m the Royal Scientist, so I have access to the rare of the rare. If _I_ can’t find something out, I don’t know who can.”

The two of them regard each other for a moment, their thoughts aligning in that stars-blessed way they tend to do, from time to time.

“Oh,” they say. “Let’s go see Asgore.”

* * *

“Well,” Asgore says, his face rather bleak, “this isn’t great, boys.”

“We know,” Grillby says, sparking yellows in agitation. “But it’s—it’s fixable, isn’t it? It’s not lethal? He’s going to be okay?”

Asgore eyes Grillby rather nervously—Gaster gets the feeling that if it _was_ lethal, that announcement would be better made somewhere less flammable. “Fixable is perhaps not the right term,” the king says warily, and Grillby flickers through a myriad of panicked colors. Gaster sets a hand on his back, trying to convey some sense of calm through his magic. (Not that he has much calm to spare— _not fixable_ is the exact opposite of what he wanted to hear, and it leaves him feeling ill and afraid.) “But it’s hardly lethal! Chronic, perhaps, but not lethal.”

Grillby crackles into a tiny red puddle on the ground, wallowing in relief. A shudder of that same relief rolls through Gaster, strong enough to make his knees weak—but he stays standing, if only for his soulmate. Gaster scoops Grillby up and holds him close to his chest, petting his little handful of flame gently. “There, there,” he says, as consolingly as he can. He tries not to sound _too_ patronizing, although the wash of relief leaves him feeling a _touch_ playful. (As playful as he can get when he’s still exhausted and chewing on the word _chronic.)_ “So, chronic. I’m going to feel this way forever?”

“Oh, dear, I hope not,” Asgore says. “It’s chronic, yes, but the good news is that the symptoms are easily manageable. You’re a vampire, Dr. Gaster.”

“A what?” Gaster asks, his brow furrowing.

“A vampire. It’s a term for those afflicted with an ancient disease—a disease rare enough that it’s nearly extinct, now,” Asgore says, leaning back in his throne and sighing softly. “Unfortunately, it seems there’s been a resurgence in Snowdin. Your attacker must have been accidentally turned. The vampires I keep tabs on would never spread their disease on purpose; that’s a terribly irresponsible thing.”

“So this disease, it—what? Prevents energy absorption from food?”

“Essentially, yes.” Asgore folds his hands in front of him. “It destroys the body’s energy conversion system—be that a biological system or a magical system.”

“And how come _I’ve_ never heard of this disease before? Doesn’t that seem like an important thing for the Royal Scientist to know about? I could have had people working on a cure!”

Asgore grimaces. “That’s been attempted before, with less than ideal results. There aren’t many vampires left, and those that are left simply want to live out the rest of their time in peace. They’ve come to terms with how they have to live, and most of them are leading very happy lives. They don’t want to bother with a cure, and I—well, I was fine with that. After all, if the disease doesn’t spread, it dies out. I had intended for it to die out with these last few individuals, but now that you’ve been created…”

“I’m not spreading it to anyone else,” Gaster says firmly. Then he falters, and Grillby inches up his arm to curl around his neck as a warm, crackling scarf. “Er—but how is it spread, exactly?”

“I don’t rightly understand the scientific complexities of it—that’s Madon’s specialty—but the gist of it involves an exchange of energies. In your case, the vampire took energy from your soul, and you took energy from their blood. I _would_ greatly appreciate it if you kept this disease to yourself. The kingdom can tolerate feeding a limited number of vampires, but too many would be quite the issue.”

“I can imagine,” Gaster says, folding his arms across his chest. “How do you feed them, then? Transfusions?”

“No, not usually. Vampires require an outside source of magic. Now, ordinary monster magic does work in a pinch, but it takes a significant amount to feed a hungry vampire—too significant for a simple transfusion. It would take pints of the stuff. The better solution would be a transfusion of soulmagic, rather than regular magic, but that’s extremely dangerous to remove by our current clinical methods.”

Gaster’s brow furrows—soulmagic _is_ a finicky thing, and a finicky thing that _fucking hurts_ to have removed, he knows now from bitter experience. He lifts his hand and rubs it uncomfortably across his own sternum, just above his soul. He assumes all vampires would be able to shred a soul with their magic, as his own attacker had tried to do, but he doubts that’s something Asgore would approve of. “So if you’re not using transfusions, what _are_ you using?”

“Well,” Asgore says, fiddling with his sleeves. He won’t meet Gaster’s eyes, and Gaster fights the urge to rattle with discomfort. “Well, usually the vampires do it themselves. They bite, and then they use their own magic to puncture their donor’s soul.”

Gaster’s soul chills all the way through, and he goes very still. “...bite?”

“What the fangs are for,” Asgore says apologetically, gesturing at Gaster’s mouth.

Gaster stares at him, frozen in sudden, abject horror. Fangs. Magic. Vampires pin monsters down and tear their throats open and use their magic to shred souls, to _torture_ other people, and Asgore _lets them?_ Gaster’s chest begins to rise and fall more quickly. Hyperventilation, here he comes.

“Now, now, don’t look so frightened,” Asgore rushes to reassure him, waving his hands in a vague calm-down gesture. Grillby burns a little more warmly against his shoulders. “It’s all very safe and consensual. Every vampire in the Underground has a select group of monsters willing to donate. It’s just like a normal magical transfusion, only there are, er, teeth and souls involved. Just a little pinch, though! From what I’ve heard, it doesn’t hurt more than a normal transfusion needle would. So really, it’s all very normal.”

Gaster can’t breathe. Oh, dear. “How much?” he whispers. “How long?”

“Well, it’s chronic, so this is going to be a lifelong need. Most of the vampires I know feed every few days. How much they take depends on them. Some require more magic than others, but a well-managed rotation of donors keeps everyone happy and healthy, so you should never have to be afraid of taking too much. As long as you aren’t, you know, _starving.”_

Gaster begins to tremble. Grillby crackles quietly in concern, blanketing Gaster in a cocoon of worried heat. Gently, Gaster hooks his hands around Grillby (a remarkably difficult endeavor, when Grillby is feeling as not-solid as he is right now) and sets him back on the ground, where he begins to bush out into a slightly-more-energetic campfire. 

“Well,” Gaster says, swallowing rapidly. “That’s. That’s a lot to take in.”

“I understand it may be distressing,” Asgore says, “and that’s alright. But you _are_ going to be okay. You just need to a little bit of magic and rest. I can help you find a rotation of donors, of course, and set you up with some of the other vampires to you can speak with them about their experiences, and—”

“Can we do that later please.” 

A concerned frown flickers across Asgore’s face. “Of course, dear boy. Just—have a care, won’t you? If you get too hungry, you could hurt someone, and we don’t want that.”

No. No, they really don’t want that. Gaster stumbles backwards a step, and Grillby whirls into his proper shape. “Wings?” he asks, his voice laced with concern. 

A dim, rushing noise fills Gaster’s skull. Grillby takes a step towards him, and all Gaster can think is how much it _hurt_ to be bitten, how _violating_ it felt to have his magic torn from his soul, and how very, very much he does not want that for anyone else in the world. The second Grillby reaches for him, he takes a deep breath and springs backwards, lashing out with what little magic he has left and tearing through spacetime.

He teleports, and he lands in his bedroom and crashes to his knees, shrieking and clawing his chest in sudden agony. His soul cramps violently beneath his sternum, and he feels his ribs begin to fracture because there simply isn’t enough magic left to keep them solid. He wails, pressing his forehead to the floor and hugging himself and hoping desperately he won’t simply fall apart and fall down and turn to dust.

...he doesn’t fall apart. The thin fractures along his ribcage stop spreading after only a few seconds, and he’s left gasping, tears streaking down his face. He can’t stop thinking about the vampire, about the bite, about how absolutely terrifying and painful and _awful_ the whole ordeal was. Oh, but the worst part, the _cruelest_ part of it all? 

He’s now condemned to make others feel the _very same way,_ if he wants to live.

**Notes for the Chapter:**

> thank u for reading this chapter of Things Keep Getting Worse Because Gaster is Scared All of the Time


	4. grillby

**Notes for the Chapter:**

> warnings: injuries, references to violence/death, dubious consent (where weird magic-drinking things are considered), self-loathing
> 
> aLSO WE HAVE SOME INCREDIBLE ART FOR THIS FIC NOW AAAAAAA!! [here's](https://carnation-damnation.tumblr.com/post/190282082495/falling-back-into-bad-habits-fanart-for) the boys lookin phenomenal and angsty by @carnation-damnation on tumblr!

Grillby comes looking for him. Of course he does. 

“Wings!” he shouts, hammering on Gaster’s front door. “Wingdings, come on, answer me! I will burn this lock out, gods, I need to know you’re _okay—”_

Gaster’s phone, which had been ringing more or less non-stop since he left the palace, chimes again. He huddles down on his bed, hugging himself harder. He knows he needs to answer Grillby or his door really will be cinders—Grillbz probably thinks he’s unconscious or dust, after that little fiasco, and Gaster can’t blame him. He feels like he should be dust, to be quite honest. If Asgore is to be believed, then the only way to make himself stop feeling this way will be to tear through someone else’s soul, and he knows perfectly well who’s going to be the first to offer.

Gaster can’t do that to Grillby. He _can’t._

...he smells smoke. 

Oh, gods, his door.

“Okay okay okay okay!” he shouts, practically flinging himself down the stairs. “I’m fine, leave that alone, _leave it—”_

“Wings!” Grillby shouts. “Wings _what the fuck!”_

His door stops smoldering. Gaster presses his back to it, panting. He can feel Grillby’s warmth through the wood. It comes in spastic, terrified waves. “I’m sorry,” he says, first. “I’m sorry I scared you.”

“You’re okay?”

“I’m okay,” he says firmly. Grillby’s flames hiss with relief, the heat outside of the door cooling some. “I just need some time.”

“Can I come in?”

“No, I don’t think that’s wise.”

“We’re supposed to be doing this together,” Grillby says. He sounds utterly miserable. Gaster hears him lean against the door, putting their backs together so that only the wood separates them—and that flimsy wood, Gaster knows, stands only as long as Grillby wants it to. The thought petrifies him. “This whole life thing, Wings. We’re supposed to be a team. Stop leaving me behind.”

“I’m not! I’m just—I’m just trying to figure this out.”

“Let me help?”

“I can’t.” Stars, his soul feels like it’s cracking. Grillby sounds _heartbroken._ “I want to, Grillbz, I really do, but I don’t want to hurt you, and I know that’s exactly what you’re going to suggest.”

Grillby huffs out a quiet laugh. “Well. You’ve got me there. It makes sense, doesn’t it? My soul is yours. My magic is yours. If you need it, take it.”

“Oh, see, there it is,” Gaster says, dragging his hands down his face. “There’s the offer. I can’t do that to you. I mean, for starters, I don’t even know _how._ And it hurts! Gods, Grillby, I can’t hurt you like that.”

“Then—I mean, it doesn’t have to be me,” Grillby says. “We can find you someone else, if you’d prefer, but we need to do it soon. You’re sick and getting sicker. Why suffer any longer than you have to?”

Gaster clicks his teeth together, hugging himself. He doesn’t want to do this. He doesn’t want to be having this conversation. He doesn’t want to be thinking about things like this. He doesn’t want to be here. He doesn’t want, he doesn’t want, he _doesn’t want any of it._

“Can I come in?” Grillby asks again, more quietly. “Please? Wingdings?”

How is he supposed to stay firm when Grillby sounds so small and lost? He sighs, shutting his eyes for a brief moment. “Alright, but you have to stay back,” he warns.

“I will.”

“Promise.”

“Cross my heart and hope to die.”

Gaster unlocks the door, then skitters away from it, watching warily as Grillby slips into his house. Grillby holds his hands up peacefully as he enters, kicking the door shut behind him. “Come on, you’re not just gonna snap and jump me.”

“I’ve wanted to bite you. I’ve wanted to hurt you. What if I’m not able to stop myself? What if I just—” His hands shake, and he chokes off around a miserable whine.

“Hey, breathe. I won’t let you do anything to me that I don’t want, and we both know I’m capable of stopping you,” Grillby assures him. That...does make Gaster feel a little bit better, and he nods jerkily. “Let’s just sit down and talk, okay?”

Gaster takes a tentative seat in his armchair, and Grillby longues on the couch. He looks far, far too calm for this situation, Gaster thinks. “So,” Gaster says, after a moment of painful silence. “At least we know what the problem is.”

“Yes.” Grillby exhales in relief. “Thank the stars. You’re going to be alright.”

“Well, _alright_ might be pushing it. I have to hurt other people to survive.”

“So that’s the big fear here? The physical pain you’re gonna cause them? If it bothers you that much, I’m sure we can find a way to get anaesthetic for them.”

“I—I guess, but the physical pain isn’t the worst part. It’s—” He gestures vaguely at his own soul, remembers the _agony,_ the sickening _fear_ it had caused him when his magic had been torn away. “It hurts. Having magic pulled out, it _hurts.”_

“What if they were unconscious when you did it?”

Gaster looks at him, horrified.

 _“Consensually_ unconscious, come on,” Grillby adds hastily. “I don’t mean just knock them out and say go. Like—surgery unconscious, you know?”

“That’s expensive, and there are risks involved. Maybe once or twice would be fine, but to ask someone to do that every few _days?_ No way.”

“Not every few days. With a big enough rotation, you’d only be feeding off of the same person—what? Once a month? Less than that?”

“Even so, asking someone to undergo anesthesia once a month for the rest of my life seems cruel and unnecessarily selfish. This whole _thing_ is cruel and unnecessarily selfish.” He folds his arms across his chest, scowling. _“I’m_ being—”

“If you say you’re being cruel and unnecessarily selfish I will bite you.”

Gaster huffs. 

“You didn’t ask for this,” Grillby points out, leaning forward. “You are taking what you need to survive and nothing more. You aren’t taking anything from anyone who doesn’t consent, so there’s hardly any _cruelty_ involved. I don’t think there’s a single cruel bone in your body.”

“I don’t—you don’t—” Gaster flaps his hands in frustration, lurching to his feet and beginning to pace across the living room. Grillby doesn’t _get it._ He doesn’t understand the terror, the agony, the _violation_ of what Gaster has to do now! It isn’t fair. It just isn’t _fair._ “I don’t want to do this! I don’t want to live this way!”

“I know. I know, and I’m sorry.” Grillby rises to his feet, too, his flames stoking hotter with his emotion—with his _grief._ Gaster can practically taste his magic, and it makes him shake with ~~hunger~~ terror. “I am so sorry, Wings. I would give anything to fix this for you, but I can’t. The only thing I can do is try to make you feel better, and I will do everything I can to accomplish that. You’re my soulmate. Taking care of you is my job, remember? So let me do it.”

“That—ha ha, that sounds familiar, doesn’t it?” Gaster says. His eyes sting. He rubs the heel of his hand over his sternum. His soul shudders beneath his touch, and he can imagine how _good_ it would feel to bite the way his teeth ache for, to take what he’s been invited to. He could feel full again. He could stop feeling so wretched and tired and miserable. 

...he could force Grillby into the same terror he himself was forced into, weeks ago.

His breathing picks up again. He shakes and shakes and shakes.

“Somebody said the same thing to me a few weeks ago. He’s pretty wise,” Grillby says, stepping towards him with a concerned frown. “Hey. Remember your breathi—”

Gaster lashes out with his blue magic, pushing Grillby away from him. “Don’t,” he says. “You said you’d stay back, you _said,_ you—” 

A crack splits up Gaster’s radius, and he shrieks—half in surprise and half in pain. Immediately, he drops Grillby and pulls his magic back into himself, trying to restabilize his form. He clamps his arm tightly to himself, trembling. Fuck. _Fuck._

“Wings!” Grillby stumbles a few steps forward before catching himself and drawing up short, his eyes wide with horror. “Are you alright, are—are you—?”

“I’m fine,” Gaster spits, backing away until his back hits the wall.

Grillby stares at him for a moment—then his eyes narrow sharply, and furious red begins to streak through his flames. “I am getting _so sick_ of being lied to,” he hisses, and the sudden bitterness in his voice digs claws at Gaster’s soul. “We don’t have time for this.”

“Time for what?” Gaster demands, baring his teeth and trying valiantly to squeeze himself through the wall. “Fuck _off,_ get away from me. I don’t want to hurt you, I—”

“That’s enough! You know I love you, you know I care about what you want, but you are _dying._ You are _falling apart.”_ He gestures wildly at the crack on Gaster’s radius, which continues to creep down, towards his wrist. “We don’t have a choice, anymore.”

Gaster feels things changing, shifting the ground beneath his feet—not in himself, this time. Oh, no. _Grillby_ is changing, digging those vicious hidden teeth of his in and bearing down with all the powerful intent he carries in his soul and so seldom brings to bear against Gaster. They teeter on a precipice, and for the first time in a long, long time, Gaster isn’t convinced Grillby won’t push them both over. 

...there is nowhere to hide, now.

“Yes we do, Grillby, yes we do, we have a choice,” he says, sudden panic sticking in his throat like bile. “Please don’t make me hurt you, please please please don’t do that you can’t do that you can’t make me please—”

Grillby whirls around and stalks into the kitchen. Gaster watches him go, torn between confusion and relief. 

“Grillby?” he calls, his voice shaky. “Grillby what are you doing?”

“You don’t have to hurt me,” Grillby says. Despite the comfort of his words, the resolve in his voice leaves Gaster rattling in fear. There’s a _but_ coming. “I won’t make you do that if it scares you so much, but you _are_ going to take what I offer.”

Gaster smells the wound before he sees it—smells the bright, hot scent of Grillby’s magic spilling from his body. His first reaction is panic, because _holy fuck Grillby’s hurt._ His second reaction, snapping viciously at the heels of the first, is _give give give give._ He staggers backwards in horror, squeezing himself into the corner of the room and clamping a hand over his mouth and nose, as though _that’s_ going to cut back on the smell. 

“Grillby, no,” he says, his eyes widening as Grillby steps back into the living room—there’s a small slit across his forearm, oozing with the white glow of his magic. Gaster’s eyes sting with the threat of tears. Gods, fuck, this is his fault—that _wound_ is his fault. If he hadn’t been so _stupid,_ so _wistful,_ if he hadn’t stopped to stare at the fucking sky he never would have been attacked, he never would have been turned into this vile creature, he never would have forced Grillby into this wretched position. If it wasn’t for him, Grillby wouldn’t hurt. If it wasn’t for him, Grillby would be _happy,_ the way Grillby’s always meant to be. “No. No no no no no.”

Regret flashes through Grillby’s eyes, but it quickly resolves itself into that stubborn determination Gaster usually adores his soulmate for. Right now it only makes him quake. “I’m sorry,” Grillby says. “I really am sorry for this. I wish to the gods you didn’t have to feel so frightened—but I would rather you feel this way than die.”

Grillby moves closer, each step firm and resolute, and Gaster huddles down in his corner and looks desperately for an escape. Grillby sees right through him—oh, of course he does—and refuses to allow him the chance to bolt. He drops quickly into a crouch before Gaster, bracing a hand on either side of him. Gaster feels very small before him, and very frightened, and—

—and very, very hungry.

His eyes flick towards the wound on Grillby’s forearm. It isn’t deep, nor does it look terribly damaging. Gaster could tend to it here; a few stitches would see it closed and on its way to healing. That should be his first (his _only)_ thought. He should be focused on rushing Grillby to the bathroom, pulling out the first aid kit and fixing his soulmate. That’s his _job._

It’s not his first thought, though. His first thought isn’t coherent—in fact, it’s barely a thought and a more of an impression, a bone-deep, starving _want._ He wants Grillby’s magic. He wants it so badly he can barely breathe, and it scares the shit out of him.

“Why did you do that?” he asks, his voice cracking. “Grillby _why did you do that.”_

“Because I _love_ you and I can’t stand watching you suffer like this, Wingdings! You’re hurting, and you just expect me to sit back and—”

“You’re the one hurting me, right now.”

Grillby flinches as though Gaster has struck him. “I don’t—I don’t want—”

“Well you _are!_ You think this is going to make me feel better? You think forcing me to do this to you is going to make me _happy?”_

“What the hell else I am supposed to do? I’m so sorry this is hurting you, but you’re—Wings, you’re—” He gestures blindly at the fractures creeping through Gaster’s bones. “Fuck. Please don’t make this harder than it has to be. Come on, I’m already hurt. Just eat. It’s going to go to waste if you don’t.”

“I don’t want to.” That is a lie. He wants to, very badly. He wants to, and he hates himself for it.

“But you’re hungry, aren’t you?”

Gaster refuses to meet his eyes. He couldn’t have if he’d wanted to, anyway. He can’t drag his gaze from that wound—that wretched, wretched wound and the magic leaking down Grillby’s forearm. His soul cramps again, raw agony, and he doubles over and hugs himself and tries desperately to hold every shattering piece of his world together.

“Oh, Wings.” Grillby’s voice sounds—sounds frightened, now. He takes a seat, reaching out and dragging Gaster into his lap. Gaster struggles to get away, but it’s a weak attempt at best, and utterly useless against Grillby’s strength. “Come here, stop fighting. I’ve got you. Just this once, okay? If you don’t like it I’ll never, ever make you do it again, but just this once—just this once, just to keep you alive, please, _please—”_

Gaster squeezes his eyes shut, a helpless whimper bubbling up from his throat. 

“Shh. Shh, it’s okay. You’re gonna be okay.” Grillby begins to rock him gently, wrapping his uninjured arm around Gaster’s chest. His other arm he keeps close—close enough that Gaster has to grip Grillby’s wrist with one hand to keep it from coming any closer. (He holds no delusions that his strength stops Grillby. If Grillby wanted to, he could easily force his magic down Gaster’s throat—but he’s far too soft-hearted for that, and he won’t do it, not unless Gaster is unconscious and seconds from dusting. At least. At least Gaster really, really hopes that’s true, or he doesn’t know his soulmate at all.)

“Grillby, let go,” he says, his voice hiccuping around a sob. “Let go. I don’t want to hurt you, I can’t do it, I can’t, please just let go.”

Around him, Grillby shudders. His flames burn low and unhappy. “No, sweetheart. Not this time.”

“But I don’t want—I don’t w-want to hurt you, Grillby please, _please.”_

“I’ll let go as soon as you take enough to heal those fractures.”

Tears—of frustration just as much as fear—begin to roll down his face, and he pushes weakly against Grillby again. It’s like pushing against a wall. “Why won’t you just leave me alone? You’re being awful, you’re b-being really awful Grillby.”

“I know,” Grillby whispers, burying his face against the back of Gaster’s neck. “I know, but I’ve let you deal with this alone long enough, and I don’t—I don’t know what else to do. I don’t know what else to do, Wings, you’ve gotta help me out here. I can’t do this alone.”

“I don’t—I just—I wanted to keep you safe.” Gaster scrubs his face against his shoulder, trying desperately to get rid of his tears, but they just won’t stop _falling._ “I wasn’t trying to—I didn’t mean to upset you, I just wanted you to be _okay.”_

Grillby’s breath hitches, and that’s when Gaster realizes he’s crying. Grillby is crying. Gaster made—he made Grillby cry.

“Grillby?” he asks, panicked—more so than even the wound on Grillby’s arm could make him. “Grillby what’s wrong?”

“A team,” Grillby says, his voice wobbling. “We agreed we were going to be a team, Wings, and _this_ is what you do? I thought we were past all this. I don’t _care_ if you inconvenience me. I don’t _care_ if I have to hurt to help you. You are allowed to take things from me—you are allowed to take my time, my energy, my magic. I want to take care of you as much as you want to take care of me, and I just—I don’t understand why you won’t let me anymore. Did I do something? Did I upset you? Is it because I killed that monster after they attacked you? Because you’re scared of me now, too? I want to fix this, I _do,_ but you have to tell me what I _did.”_

“What? What, no, no no no—” He squirms, but Grillby still refuses to let him move. He collapses back against Grillby’s chest instead, sucking in a shuddering breath. His soul tears at his throat when he scents Grillby’s magic. “No, it wasn’t you at all. It’s my fault, it’s all my fault. Don’t you get it? I was an _idiot._ I let that vampire bite me, I let them turn me into _this,_ and that’s why I’m going to h-hurt you. It’s my fault. I deserve this, I was so _stupid,_ and I hurt you, I _hurt you I keep hurting you Grillby I’m sorry I’m s-so sorry so fucking so-sorry—”_

Grillby’s grip around him tightens, and then there’s a mouth pressed to his temple, his cheek, his jaw. Heat blisters away his tears, and he sobs and shakes himself apart. _“No,”_ Grillby says, his voice relentlessly firm. “No, this isn’t all your fault. Don’t you dare think that. It was that bastard’s fault for attacking you—you didn’t ask for any of this.”

“I d-didn’t tell you, I messed up, I _messed up—”_

“Yes, alright, that part’s your fault,” Grillby admits, hugging him tightly. “And yes, you messed up, Wings, but _that’s okay._ I am mad as fuck at you, and I’m going to yell at you later, but I am _going to forgive you._ I love you, alright? You don’t have to be perfect, you don’t have to earn my love. You’re allowed to make mistakes. Of course I don’t like it when you hide things from me, but it’s not the end of the world. We’re going to get through this, just like we’ve gotten through everything else—because we’re a _team.”_

“You still—” Gaster’s chest hitches. His soul aches with something far beyond hunger, and when he speaks again, his voice is very small. “You still want me?”

“Always,” Grillby says fiercely.

“Even if I’m—like this? Some kind of evil thing that has to—”

 _“You are not evil._ If you say something like that again, I’m going to get pissed.”

“You’re a-already pissed,” Gaster says, laughing miserably. 

Grillby hesitates, then admits, “Well, you’re right. I’ll get even more pissed if you keep saying shit like that about yourself, though.” He sets his chin on Gaster’s shoulder, sighing out a breath of weary gray smoke. “You wanna know how you can make it up to me?”

Gaster looks bleakly at Grillby’s wounded arm. He gets the feeling he already knows the answer to _that._ “How?”

“Say sorry.”

“What?” He blinks—alright, he wasn’t expecting that. That’s much easier than anything else Grillby has asked him to do tonight. Much, much easier. He will gladly apologize to Grillby all evening, if it eases Grillby’s soul at all. He will grovel, to get back on Grillby’s good side. He will lick _so many_ boots. “I’m sorry, Grillby. I’m really sorry.”

“Not to me. _I’m_ not the one you insulted.”

Gaster winces, turning his face away from Grillby’s. Grillby seizes the chance to kiss the side of his throat, and a full-bodied shiver goes through Gaster. He had expected a touch like that to rile his fear back up, to remind him of the vampire that tore through his soul without a single speck of care for it, but this is—this is Grillby. Grillby would _never_ do that.

And yet here he is, asking Gaster to do it.

“Sorry,” Gaster whispers.

“For what?”

“For saying that.”

It’s as vague an apology as he can make it, but Grillby mercifully accepts it. He gently hooks his fingers around Gaster’s chin, guiding Gaster’s head back around and bringing his wounded arm closer. “Apology accepted. Now you need to eat—gods, you must be starving.”

Gaster shakes his head again, then hesitates. “I don’t—I—”

“I know you don’t want to. I know this is frightening and awful for you, and for that, I’m sorry. If you can’t do it for yourself, don’t. Do it for me, this time. Do it because I am _terrified,_ Wings. I am so scared of watching you fall apart and being helpless to do anything about it. Do it because I’m _begging_ you to, because I hate seeing you this miserable, because I would give anything in the world to make you happy and safe again but by the stars, I can’t do that alone. This life thing’s a team effort, remember?” His voice cracks again, his flames wilting, and he presses his face to the back of Gaster’s neck. His next words are hoarse and soft. “You remember, right?”

Gaster presses his hand to his mouth, his breath quavering. He remembers. He...doesn’t think he ever truly forgot. He simply ignored it for as long as it was convenient for him. How easy it is to forget that there’s always another soul he carries with him—his life is not his own, not any longer. It hasn’t been since the day he met Grillby.

“Yeah,” he whispers. “I remember, Grillby.”

“So will you—?”

He nods shakily, prying his hand away from his mouth and turning his eyes back to the wound on Grillby’s forearm. Oh, stars, he feels ill. Perhaps this is for the best (Grillby does so rarely lead him astray), but that doesn’t stop him from feeling like a piece of utter garbage about this whole arrangement. 

He’s going to hurt Grillby. (He’s going to hurt Grillby _even more.)_

“Poor thing.” Grillby rubs his cheek against Gaster’s, crackling unhappily. “All month? All month you haven’t eaten?”

“I tried. I tried to eat but it never—it never stayed down, I couldn’t do it, I’m sor—”

“You don’t have to apologize anymore. We’ll talk more later, after you’re feeling better. We have a lot to talk about.” Grillby brushes his fingers across Gaster’s teeth. “Open.”

“Promise you’ll stop me if it hurts too much,” Gaster says, trying his best to harden his voice. “Promise. Promise you’ll keep me from taking too much, because I don’t know if I’ll be able to stop myself.”

“I promise. I can handle you, little one.” Flames kiss the back of his skull, the nape of his neck, the curve of his shoulder. Grillby’s thumb rubs the corner of his mandible, coaxing him to open his mouth and take. “Trust me. You remember how to do that, too?”

Gaster swallows, and he opens his mouth, and he trusts. 

“Good,” Grillby praises—a flurry of kisses cross his face, doing their best to distract him as Grillby’s arm moves closer. Flames tickle at his teeth, the corners of his mouth, and he feels the core of Grillby’s arm fit itself in his jaws. “There we go, good job. Take what you need. I want you to. I want this.”

Gaster’s eyes sting, and squeezes them shut as he manifests his tongue and drags it across Grillby’s wound. For a moment, he’s...confused. This is strange, and definitely kind of gross. This is—how does he even do this? Oh, gods, is he just going to sit here with Grillby’s arm in his mouth for five minutes? That’s going to get really awkward really fast. 

Fortunately, his brand-new instincts come to his rescue, unfurling themselves with a ravenous throb of hunger, and he’s biting before he can even think to stop himself. His teeth slide easily into Grillby’s wound, and if Grillby wants to cry out, he does a damn good job of stopping himself. (Gaster has no doubt he means to hide his pain as much as possible. Wouldn’t want to spook Gaster again, would he? The thought is a bitter one, but it’s not enough to stop him now that he finally has _food.)_

The prick of his teeth stirs up the magic flowing through Grillby’s arm again, and Gaster sucks it from Grillby’s core into his mouth. It trickles through his teeth, bathes his tongue, tastes like grease and fire and smoke. It dissolves in a flush of energy, and Gaster gasps and shudders and begins to suck harder, gulping down greedy mouthfuls of Grillby’s magic—but it’s not enough. This isn’t the magic he needs. Oh, this magic is _good,_ but it’s hardly enough to sate his starved soul. What he needs is deeper.

His instincts guide him through the next step, too. He is grateful and utterly terrified by them all at once. He reaches out with his magic, and he feels Grillby’s soul pulsing within his core. It greets him warmly, and their magic curls together, achingly familiar. Gaster manages a warped, shaky purr, and Grillby croons softly at him.

“There you go,” he murmurs, cradling Gaster’s skull. “There we go, sweetheart, that’s it.”

Then Gaster’s magic sinks its own brand-new fangs into Grillby’s soul—he fully expects to feel a wash of pain and terror from his partner, but he feels no such thing. Grillby’s soul doesn’t even bother to recoil. Instead, it preens and stretches for Gaster, more than willing to be taken. Gods, it would be so easy to maim, to _kill,_ this way.

Gaster would _never._

But he does finally take what Grillby so readily offers. He drags magic from the core of his soulmate’s being, and it stains his teeth red and begins to finally, _finally_ soothe the hollow ache in Gaster’s own soul. His breath hitches, and he is _so glad_ he told Grillby to stop him, because there’s no way he could stop himself right now. Even the thought of unlatching his teeth and pulling away seems like an impossible flicker in his mind.

“Good, that’s good, Wings,” Grillby murmurs, which is absolutely the last thing Gaster thinks he should be saying in this position. Doesn’t he know Gaster’s hurting him? Perhaps he’s alright with it because it’s necessary, but he shouldn’t be _happy_ about it. He must be so frightened. His soul must hurt the way Gaster’s did, even if Gaster can’t _feel_ it hurting. Just thinking about what Grillby must be going through is enough to catch a whine in Gaster’s throat, and then Grillby’s hand smooths down his spine, warm and solid and soothing. “Shh, baby boy, shh, you’re doing so well. Everything’s fine.”

Gaster gulps desperately—sobbing while drinking his soulmate’s _literal soul_ isn’t exactly something he wants to try. Choking would be a real waste of valuable resources. In spite of that, tears continue to roll down his cheeks. He is so _furious_ with himself for this whole situation, but he’s also so, so selfishly relieved. The hunger that has plagued him for nearly a month now finally seems to be settling—but gods, this is a drop in a bucket. Gaster is going to need so much more. Gaster is going to need more than even his powerhouse of a soulmate can give him, and it petrifies him. He’s going to take too much. 

So it is that several minutes later, when the cracks through his bones have finally healed himself and he feels some semblance of control, he tears his mouth away from Grillby’s arm, gasping. “Okay?” he asks, first, because that’s the most important thing. “Grillby are you okay?”

“I’m fine,” Grillby assures him, squeezing him gently. He keeps his injured arm well within biting distance. “But you’re not done.”

“I’m going to take too much.”

“No, you won’t. Trust me to stop you.” Grillby kisses the side of his skull. “I know my limits, and we aren’t even close. You’ve been starving for a month, Wings. Be selfish for half a second already.”

“It’s not fair.”

“No. Maybe not. But hey, who’s keeping score?” Grillby ruffles a hand across Gaster’s skull playfully. “Not me, and it shouldn’t be you.”

Gaster wipes his eyes, breathing shakily. His soul still pangs with hunger, and hearing that Grillby _wants_ him to continue—gods, it’s hard to keep still. His teeth throb with want. “Does it hurt?”

“The bite did,” Grillby admits, leaning their heads together. “But it was like Asgore said—just a little pinprick.”

“And the—the—” The literal, you know, _eating his soul_ part.

“No. Nothing else hurts. It just feels warm, and fuzzy, and like—” He squints. “Kind of like when we blend our magic. It’s peaceful.”

“Peaceful?” Gaster’s brow furrows. That was not his experience at _all._ “You’re not scared? You’re not just lying to me to make me feel better?”

Grillby shakes his head adamantly. “No. I promise.” He pauses for a moment, closing his eyes. Red simmers through his flames, but Gaster doesn’t think that anger is directed at him, this time. “...it hurt you a lot, didn’t it?”

Gaster presses his mouth to the crook of Grillby’s elbow, nodding miserably. 

“Were you scared?”

“I was so scared,” he whispers. He tastes Grillby’s soul on his tongue with every word. “I thought—that vampire, they just reached in and they _took,_ and nobody should ever—nobody’s allowed to—my soul, they took part of _my soul,_ n-nobody but you should ever even touch that and they j-just _stole it—”_

“Oh, oh oh oh, shhh.” Grillby hugs him as he begins to weep again, feeling more exhausted and wretched and awful than he ever has. Gods, he didn’t even feel this bad the night the actual attack had happened. “I know. That must have been so frightening for you.”

“They shouldn’t have done that—shouldn’t have done that to _anybody,_ it’s not _right,_ it’s not _fair,”_ Gaster says, anger prickling between his ribs. He sniffs in indignation, tears dripping off of his jaw to sizzle against Grillby’s arm.

“No, they shouldn’t have done that,” Grillby agrees. Oh, his soulmate is so good at the _validating emotions_ thing. Gaster sniffles in appreciation. “Not to you or anyone else. That was very cruel of them. You certainly didn’t deserve it.”

“No! I didn’t!” Gaster says, scrubbing at his eyes. The words bring with them a sudden, sharp clarity. “I didn’t want that. I didn’t _ask_ for that! And—and now because of them I’m a _mess,_ and I’m scared all the time, and my teeth hurt, and it fucked up my relationship with _you,_ and I’m always _so hungry.”_

Grillby begins to rock again, slow and steady, and Gaster falls limp against him, too exhausted to even make an attempt at remaining stiff and angry. (But by the _gods_ is he angry at that vampire, and will continue to be so later, probably after a nice long nap.) “It’s okay,” Grillby says. “It’s okay that you’re feeling this way. I know it’s unpleasant, but we’re going to make you feel better. You’re _going_ to feel better, Wings. This won’t last forever.”

“Did you miss the part where Asgore said _lifelong?”_ The words would be bitter, if he had any energy left for such a tone.

“Alright, so the vampire thing might last forever,” Grillby concedes, “but the symptoms won’t. You aren’t going to be hungry for much longer. You’d be a lot less hungry now if you’d just eat, you stubborn thing.”

Gaster swipes at his eyes before glancing back at Grillby’s arm.

“It’s okay,” Grillby repeats. “Go ahead. Let me tell you when to stop.”

Gaster...still hesitates.

“Hey.” Grillby’s voice falls soft and serious. “You aren’t doing to me what that vampire did to you. This is not the same thing _at all._ I _want_ this. You are not scaring me. You are not hurting me. I am _fine,_ and I swear I’ll tell you if that changes.”

“Pinky swear.” Gaster holds up his hand, and Grillby hooks their pinkies together.

“Pinky swear.”

Gaster still doesn’t feel good about the whole thing, but...he feels better. He leans forward, and Grillby is quick to bring his arm back up so Gaster can settle in again. With each suck and swallow, he has to remind himself that _Grillby is fine_ and _Grillby wants this_ and _you aren’t hurting him, aren’t tearing his soul to pieces, aren’t_ violating _that intimate, precious part of him._ It helps, some. Grillby continues to rock him, crooning soft encouragement as he drinks.

“Good, good boy, Wings,” he says, dragging his fingers up and down Gaster’s side. Gaster hums quietly at him, leaning into his hand. His swallows are slower, now, less frantic—secure in the knowledge that this meal doesn’t plan to go anywhere for quite some time. “Good job. You don’t have to be scared right now. I’ve got you.”

Gaster leans back against his chest, fitting his skull beneath Grillby’s chin. For an act so macarabe, it’s strangely peaceful. Grillby continues to rock, and Gaster drinks, and slowly slowly slowly the yawning chasm in his soul begins to fill. He starts taking his time with his meal, pulling back to lave his tongue across the wound in Grillby’s forearm, lapping up the stray magic he’s missed. He licks the excess from his teeth, then settles his mouth back into place when Grillby nudges him to. 

“Feeling better?” Grillby asks, kissing the nape of his neck. Gaster nods, trying to keep his teeth from jostling against Grillby’s arm. “I’m glad. You don’t deserve to feel the way you’ve been feeling. You don’t deserve to be scared and alone and hungry. You know that, right?”

Gaster...can’t quite say yes, and he knows Grillby knows that, because a sour tinge runs through his magic. 

“Oh, Wings,” he says softly. “We’ve got some work to do—but that’s alright. These things are a lot easier when we work together, huh?”

Gaster’s breath shivers, and he hums quietly in agreement. He closes his eyes and mouths gently at Grillby’s arm to encourage the magic there to flow into his mouth. It’s so _willing_ to come to him. There isn’t a speck of fight in it. After a few more moments, Grillby leans his head back against the wall with a soft thump. Gaster makes a garbled attempt at speech, and Grillby hushes him.

“I’m okay,” he says. “Just resting. I’ll tell you when we’re done.”

Gaster hesitates, and then he takes a deep breath and he trusts. He suckles softly at Grillby’s arm for what feels like a small eternity—but is, he can only assume, closer to fifteen minutes. He isn’t _full_ when Grillby stops him. He assumes he’s only a little more than halfway to where he should be. It doesn’t matter. When Grillby tells him to stop, _he stops._

That, he realizes, is the difference between him and that _fucker_ who bit him.

“Okay,” Grillby says, touching the side of Gaster’s skull gently. “I think that’s about all I can give you right now, little one.”

Gaster unlatches his teeth, lapping the magic away from Grillby’s wound. He feels dazed and soft and sated, and quite honestly ready for a nap, but he has a soulmate who needs tending to first. “You’re okay?” he asks gently, turning around in Grillby’s lap—a movement which Grillby finally decides to allow. 

“I’m okay. Just tired, that’s all.”

Gaster nuzzles up against his face, wrapping his arms around his neck to hug him. “Thank you,” he says, soft and reverent. “Thank you, Grillby.”

“Anything for you.” Grillby braces a hand across his back, crackling softly at him. “Don’t be afraid to come to me next time.”

“I’ll try not to be.” He kisses Grillby’s cheek, then leans back. He cups Grillby’s face in his hand, studying him carefully. He _looks_ alright. His flames are dimmer than usual, but not dangerously so, and they still dance to greet Gaster’s hand where it touches them. “Stay here, okay? I’ll be right back.”

Grillby watches uncertainly as Gaster darts from the room, and only relaxes once he returns with the first aid kit—he’s not as nonchalant about this whole situation as he seems. He rarely is. Fortunately, Gaster’s got a practiced eye when it comes to seeing through him. 

“Hey,” he says, kneeling in front of Grillby and meeting his eyes. “We’re gonna be okay.”

A faint smile flickers across Grillby’s face. “You think?”

“I know.” He leans forward, kissing Grillby’s forehead. “We can do anything together, right, sparks?”

Grillby’s smile is a little brighter, this time. “Right.”

Gently, with all the precision he has, Gaster stitches and bandages the wound in Grillby’s forearm. “Does it hurt?” he asks, once he’s finished.

“Only a little,” Grillby assures him. “You did a good job.”

“Nothing less than you deserve, my dear.” Gaster helps Grillby to his feet, herding him towards the couch. They both collapse together, a tangle of tired limbs and drained emotion. “Do you want food or anything?”

“You know,” Grillby says, rubbing the back of Gaster’s neck gently, “I’ve actually got a real craving for hamburgers.”

Gaster chuckles, already moving to push himself up. “Well, I won’t be able to best your grilling, but I’ll give it a shot.”

“In a little while. Stay here with me first.” Grillby rolls over, squashing Gaster beneath his weight. Gaster sighs in pure contentment. Oh, how good it is to be squashed. “Rest.”

“Mm, okay,” Gaster agrees, and he’s ecstatic to discover how easy it is to do so. For several long moments, the two of them lay and breathe in silence together. Then, quietly, Gaster asks, “Hey, Grillby?”

“Hm?”

“I think maybe I need therapy.”

“Yeah, I think that’s probably a good idea. We can start looking for someone after dinner.” Grillby burrows into the crook of his throat, and Gaster runs one hand gently up and down his side. “I’m proud of you.”

The words send a warm flush through Gaster’s bones, and he cradles the back of Grillby’s head and sifts his fingers through the flames. “Thank you. I’m proud of you too. And I’m—I’m really sorry about how I’ve acted. It wasn’t fair to you.”

“No, it wasn’t, but—like I said, I forgive you. We’ll get through it. Just try not to do it again, okay?”

“You’ve got yourself a deal.”

They lapse into silence again, and Gaster rubs his fingers across Grillby’s back and shoulders, coaxing him into relaxing. “You should drink some butane,” he muses sleepily, and Grillby groans. Gaster can’t help but laugh at the irony. “Oh, come on! If I can drink your _soul_ to feel better, you can handle a few swigs of butane.”

“I suppose,” Grillby says, with a put-upon sigh. When Gaster start to squirm, he grumbles and settles more heavily against him. “Later. Sleep now.”

“Right, right, we’re sleeping.” Gaster kneads the back of Grillby’s neck, and Grillby stretches and chuffs happily. Silence, again, for a few more minutes. Gaster’s eyes feel heavy, his bones loose and finally, _finally_ warm. His soul still aches for more magic, but it’s an ache that’s easy to ignore, after the shattering agony of today. He’s _almost_ drifted to sleep when he remembers, with a startled jerk, something vitally important. “Grillby? Hey Grillby?”

Grillby groans.

Gaster turns his head, clicking his teeth across Grillby’s temple. “I love you.”

The fire on top of him burns warmer, flames licking affectionately at him. He teases at them with his fingers, and Grillby sighs happily, nuzzling into the crook of his neck—safe, secure. “I love you too, Wings. Now, by the gods, go to _sleep.”_

Gaster laughs, and he holds his soulmate a little closer, and he sleeps.

**Notes for the Chapter:**

> aaaaand that is it for the main story!!! short n sweet! there'll be a short epilogue, so be on the lookout for that in the next couple of weeks :D


	5. hamburgers

**Notes for the Chapter:**

> warnings: discussions of past trauma, references to symptoms of ptsd, the boys bein handsy ;)

“I could do a better job,” Grillby says, sulkily eyeing the fire Gaster has coaxed to life in the grill. “It’s burning too hot.”

“Jealousy doesn't look good on you, dear,” Gaster teases.

“It doesn’t know what it’s doing.”

“I should hope not. It’s non-sentient.”

“I could help.”

“Nope! You do your job.” He flips the burgers on the grill, pressing them down with the flat of his spatula the way he’s seen Grillby do time and time again. “Don’t worry, I’m not going to leave you for this little grill fire, no matter how cute it is.”

Grillby grumbles playfully as he goes about toasting hamburger buns. The buns have been drizzled carefully with oil and sesame seeds, and they smell  _ heavenly  _ as they warm. As soon as they’re toasted, Grillby sets them down on his plate, then begins layering on the toppings—crisp lettuce, ripe tomatoes, crunchy red onions and sharply-scented pickles. Stars, Gaster wishes he could eat that. 

Ah, well. He’s about to have something better.

When the hamburgers are almost done, Gaster adds a couple of slices of cheddar cheese and lets them melt. Once the cheese looks perfectly gooey, he slides the hamburger patties onto the little beds Grillby has so lovingly prepared for them. “Huzzah!” he says, clapping his hands together. The right one barely aches, now, after so many months of healing. “If that isn’t a perfect hamburger, I don’t know what is.”

“They do look pretty perfect,” Grillby concedes, drizzling on mustard and ketchup. Gaster puts their ingredients away, then slides into a seat at the table alongside Grillby. “We make some awesome stuff together.”

“Hell yeah we do.” Gaster props his face in his hands, watching as Grillby begins to eat. “Maybe you should hire me at the bar. I’m getting pretty good at this cooking thing.”

“What, and take you from your lab? Come on, you’d hate that.”

Gaster inclines his head. “Eh, you’re probably right.”

“You’d make a good waiter, though. You could draw in the crowds with that pretty face of yours,” Grillby says, grinning.

“Oh, please.” Gaster can’t help but grin back—Grillby’s happiness has always been infectious. Besides, Grillby likes his smile. His eyeteeth have finally finished growing, and they’ve left him looking quite fangy. Grillby insists it only makes him cuter. (“Like a kitten! Like a little kitten, with your fangs just poking out, I’m  _ telling  _ you Wings, stop laughing at me—”) It made kissing a dilemma, for the first few weeks, but they’ve worked around that with quite a bit of  _ practice.  _

“So,” Grillby asks, after swallowing a mouthful of his burger, “how was your session with Pierre today? Learn anything exciting?”

“Oh, it was good.” Gaster brightens, sipping at his water. “We talked a lot about communication. It was a good break from talking about all the, uh, other stuff.”

“How  _ is  _ the other stuff?”

“Better. You know. It’s slow going, but Pierre said it would be. I haven’t had a nightmare in over two week, though, so that’s pretty neat! I mean, I’ve probably just jinxed it, but—” He chuckles, swirling the water in his glass contemplatively. “That’s okay. I feel like I’m less stressed, y’know? I don’t think about it as much anymore.”

“I’m glad.” Grillby crackles warmly, flickers of bright green happiness dashing through his flames. “I’m glad this is working for you. Now, how about your dinner with Joan last week? I mean, I know you said it went well, but how well?”

“Oh, super well! She was very sweet and understanding. We took it slow.”

“Were you scared?”

“I mean, a little, but not nearly as much as I used to be. She said it didn’t hurt at all. She called me  _ polite.”  _ Gaster squirms in delight. “Said she barely noticed when I got to her soul.”

“That’s my boy. You’ve got a gentle touch.” Grillby reaches out, brushing a thumb along his jaw and humming happily. Gaster turns his head, brushing a kiss across his fingertips.

“Madon—that’s the vampire in Hotland—said I have a soft mouth. I think she was comparing me those hunting dogs that carry quarry in their mouths? But, like, I’ll take it.”

Grillby laughs, sparking with delight. “A hunting dog, huh? What a compliment.”

“I know, tell me about it. Hey, what about your meeting with Muffet this morning? How was that?”

A sour look flashes across Grillby’s face, and Gaster can’t help but giggle. Their rivalry amuses him to no end. “Oh,  _ her.  _ She tried to convince me that donuts would make good hamburger buns. It was a painfully obvious ploy to get me to buy her product. Also, gross? She has no tact whatsoever.  _ I  _ taught her that I’m not so easily manipulated—and how to make savory bagels.”

“Ooh, giving away such valuable secrets already? I’d almost think you were becoming friends.”

Grillby’s flames snap and curl in offense. “What? That’s nonsense.”

“Okay, okay,” Gaster says, hiding his grin behind his hand. “Whatever you say, sweetpea.”

The rest of Grillby’s dinner follows in a similar manner—they share stories and ideas and affection until Grillby finishes off the last of his second burger and stretches back in his seat with a satisfied groan. Then he offers Gaster an expectant look. “Hungry?”

Gaster nods earnestly, leaning towards him.

“Come on, then.” Grillby leads the way to the living room, taking a seat on the couch and opening his arms. Gaster curls up in his lap, already purring, and butts his head up beneath Grillby’s chin. Warm arms close around him, cradling him close. Gods, is there anything better than Grillby snuggles? “Whenever you’re ready.”

“‘kay,” Gaster says—but there’s no need to  _ rush  _ these things. He is a polite, soft-mouthed vampire, after all! Also he is in love, and he wants Grillby to feel nothing but good things. For a while, he simply sits and basks in Grillby’s warmth and runs his hands all over his soulmate because he  _ can.  _ Grillby leans into him with happy little flickers, his eyes closing. “You’re incredible, you know that, Grillbz?”

“So I’ve heard,” Grillby says, a fond smile crossing his face.

Gaster shuffles around to face him, gently dragging his hands up and down Grillby’s sides. He slips his hands down, tucking them under the hem of Grillby’s shirt. “May I?”

“Mm, only if you take yours off, too.” 

Gaster grins, gently pulling Grillby’s t-shirt off and tossing it into the armchair next to the couch. “You’ve got yourself a deal, babe.”

Grillby divests Gaster of his sweater, then drags him down and into a sweet kiss. His flames lick between Gaster’s teeth, and Gaster shivers and presses closer. When they part, Grillby cups his face, rubbing a thumb across one of Gaster’s fangs. Gaster turns his head, taking Grillby’s thumb between his teeth and biting gently—not enough to sting, let alone to break through Grillby’s core. Nevertheless, a pleased shiver writhes its way through Grillby’s flames and leaves Gaster feeling smug and satisfied. 

He reaches out, setting his palm against Grillby’s chest and summoning his soul. He cradles it in his hands, smoothing his thumbs across its surface. “Hello, little one,” he greets it affectionately, and Grillby’s magic stretches eagerly for him. “How are we today?”

“We are phenomenal,” Grillby says, as Gaster rifles through his stats just to make  _ sure  _ he’s in shape for this. Grillby’s magic begins to twine with his own, coiling up his fingers and teasing at the magic in his own bones. Stars, that feels good. Gaster shivers, leaning forward to press his teeth to Grillby’s soul in a gentle kiss.

“Wings? I want to see your soul.”

“It’s all yours, hotshot.” Gaster brings his soul forward after dismissing Grillby’s—it looks damn well better than it did months ago, bright and flushed full with magic. Grillby reaches out to cup it in his hands, warm and steady and  _ perfect.  _ The way Grillby looks at it, though, rapt and just short of worship—well, that makes him feel a little shy. He tears his gaze away, his cheeks warm. “You’re being sappy again.”

“Always.” Grillby leans forward, kisses Gaster’s soul. His flames curl against it, and they tickle enough to have Gaster squirming, a smile flickering across his face. “You have a beautiful soul, my dear.”

“I don’t really thin—”

Grillby’s teeth brush across his soul—wicked points Gaster rarely gets the chance to see, but by the  _ gods  _ can he feel them. His breath hitches. When Grillby’s tongue follows suit, laving softly across his soul, Gaster gasps and reaches forward to cradle the back of his soulmate’s head, holding him close. It’s a fight to keep himself from keening at the feeling, but he has a  _ smidgen  _ more pride than that. 

Grillby chuckles, low and raspy, before murmuring to his soul, “You’re still hungry, aren’t you, beautiful? Maybe you should ask our Wings if he’ll feed you before we get any rowdier than this.”

“Honestly,” Gaster says, sighing out a shivery breath as Grillby kisses his soul again. “I can’t focus while you’re doing that.”

“Mm, pity. I’ll have to try again after you’ve eaten.” He brushes his fingers across Gaster’s soul in a farewell, then dismisses it back to the safety of Gaster’s ribcage. He offers Gaster a wicked grin as he sits back. “You’re just so sweet—I may have to have dessert after all.”

Gaster splays a hand across Grillby’s face, pushing him back against the couch with a distraught whine. “Stoooop! You’re making me want to kiss you more.”

“Well, we can’t have that, can we?” Grillby laughs, dragging Gaster down against him. He tilts his head to the side, and Gaster burrows into the crook of his neck, inhaling deeply—trying to focus on being hungry instead of horny, which is a fight and a half.

“I mean, we could,” Gaster says, smoothing his hands down Grillby’s chest and across his abdomen. Then he leans up, capturing Grillby’s mouth with his own again. He purrs into their kiss, kneading against the soft flames of Grillby’s stomach and flicking his tongue across the wicked points of Grillby’s teeth. Grillby shivers beneath him, and Gaster pulls back, resting their foreheads together. “I wouldn’t complain.”

“You’re insufferable.”

“You like me that way.” He leans in for another kiss, because kissing Grillby is just  _ so much fun.  _ At the same time, he trails his hands down, teases at the waistband of Grillby’s sweatpants. Grillby’s breath hitches, and Gaster can’t quite keep himself from grinning into their kiss. Then Grillby clamps one hand at the small of Gaster’s back, and his other hand comes down firmly against Gaster’s ass. Gaster yelps in dramatic affront—the swat didn’t hurt, but it damn well got his attention, which he supposes was the point.

“That’s enough, little pest,” Grillby scolds. “You need to eat before we do anything else.”

Gaster grumbles in betrayal, but he’s quick to burrow up against Grillby’s throat again, sucking leisurely at the flames there. “Am I to assume  _ anything else  _ means sexytimes?”

“Yes, Wings. _ Anything else _ means sexytimes.”

Gaster cheers, wiggling happily and nipping his excitement into the core of Grillby’s neck—playful nips, and nothing more, nothing to close to what he needs to do to get at Grillby’s magic. After all, he’s had quite a bit of practice doing this, these last few months, but it still makes him...nervous. He’s much more comfortable simply mouthing at Grillby’s throat, slow and relaxed and loving the way it makes Grillby’s flames shiver around him in lazy pleasure. He could do that for  _ hours— _ but Grillby’s hardly going to let him, of course.

“Hey,” he says, patting Gaster’s ass when he hasn’t bitten after a few minutes. “Pay attention.”

Not  _ pay attention to me,  _ of course. Gaster knows Grillby wouldn’t ask that of him (leastways not so easily). It’s  _ pay attention to you.  _ That’s...a much more difficult thing to do, but he tries. He  _ is  _ hungry. There’s a low, uncomfortable prickle in his soul that demands his attention. It still feels selfish, taking so much from everyone around him, but he’s trying to work through that. (His therapist helps quite a bit—and so does Grillby, of course.) Now, instead of turning his back on what he needs, he opens his mouth and braces his fangs against Grillby’s throat. Grillby moves a hand up to cradle the back of his head, encouraging him to stay in place. 

“It’s okay,” he murmurs, rubbing the nape of Gaster’s neck. “It’s okay, baby boy, you can bite. Take what you need.”

So Gaster takes a deep breath, squeezes his eyes shut, and takes. His fangs sink easily through Grillby’s core—he feels the flames around him flinch, and he whines an apology at Grillby. 

“Just a sting,” Grillby reminds him. “Don’t think anything of it.”

Gaster suckles at the tiny pinprick wounds he’s made, and Grillby’s magic trickles into his mouth, blissfully warm. Then he stretches with his own magic, opens Grillby’s soul, and begins to suck more heartily. Grillby leans back with a deep sigh, one hand still cupped at the back of Gaster’s skull, a silent reassurance— _ keep going, don’t stop, I want you right where you are.  _

“Good,” he murmurs. “Good boy, Wings, that’s it.”

Gaster still doesn’t feel particularly  _ good  _ about this whole thing, but he’s starting to feel less  _ bad,  _ and that’s something, he thinks. He kneads Grillby’s shoulders as he drinks, and Grillby relaxes beneath him, warm and pliant and willing. Gaster does his damned best to make Grillby feel good while he does this—or, at the very least, to distract him from what’s happening. He traces the tips of his fingers over Grillby’s chest and stomach and feels him shiver. Every few minutes, he stops to lave his tongue soothingly across the wound in Grillby’s throat.

Gaster nurses at Grillby’s throat until his soul feels full and sated, and then he stays, after that, reluctant to unlatch. The way their magic flows together like this—it makes him feel so  _ close.  _ Still, he doesn’t want to keep Grillby’s wound open longer than he has to. He draws back, purring hard at Grillby in gratitude, and Grillby beams at him and lights up the entire world. This whole  _ taking _ thing, it’s not easy, and Gaster doubts it ever will be—but he has a pretty damn good teacher, and as a team, they’re capable of just about anything.

**Notes for the Chapter:**

> aaaand that's a wrap on 'learning to take'! thanks so much to everyone who came along on this fun lil journey!! (and special thanks to anchestor, again, for all of the fantastic inspiration!!!) you guys are the best!!! i doubt this is the very last time we'll see these boys—i'm sure they'll pop up in oneshots from time to time, and if there's anything you particularly wanna see written about 'em, you can pop on over to my [tumblr inbox](https://parsnipit.tumblr.com/) and send a prompt. until then, i hope you guys have a great time, and remember that relationships are as much about taking as they are giving! <3


End file.
